Symposium : Q
Novel materials and fabrication methods for new emerging devices
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| 09:00 | Semiconductor nanowire devices for photonic and electronic applications Authors : C. Ronning Affiliations : Institute for Solid State Physics, University of Jena, Jena, Germany Resume : Semiconductor nanowires are of major importance within the area of nanotechnology, and are usually synthesized using the so-called vapor-liquid-solid (VLS) mechanism. They serve as both functional units and as the wires that access them; therefore, they are ideal building blocks for multifunctional nanoscale devices. Applications and proto-type devices based on semi¬conductor nanowires have been realized in various areas: in electronics, photonics, mechanics, and sensors. I will just summarize and focus this presentation on the use and assembly of zinc oxide nanowires for photonic and electronic applications: this will include waveguiding [1], light emitting diodes [2], lasers [3], field effect transistors [4], and chemical and biological sensing [5].
[1] ”High order waveguiding modes in ZnO nanowires” T. Voss, G.T. Svacha, E. Mazur, S. M?r, C. Ronning, D. Konjhodzic, F. Marlow, Nano Letters 7 (2007) 3675
[2] ”Scalable fabrication of nanowire photonic and electronic circuts using spin-on glass”, M. Zimmler, F. Capasso, D. Stichtenoth, C. Ronning, W. Yei, V. Narayanamurti, T. Voss, Nano Letters 8 (2008) 1695
[3] „Laser action in nanowires: Observation of the transition from amplified spontaneous emission to laser oscillation”, M. Zimmler , J. Bao , F. Capasso , S. M?r , C. Ronning, Appl. Phys. Lett 93 (2008) 051101
[4] “High performance ZnO nanowire field effect transistors”, Pai-Chun Chang , Zhiyong Fan , Chung-Jen Chien , Jia Grace Lu , D. Stichtenoth , C. Ronning, Applied Physics Letters 89 (2006) 133113
[5] “Biofunctionalization of zinc oxide nanowires for DNA sensory applications” R. Niepelt, U.C. Schr?, J. Sommerfeld, I. Slowik, B. Rudolph, R. M?r, B. Seise, A. Csaki, W. Fritzsche, C. Ronning, Nanoscale Research Letters 6 (2011) 511 | 4 17 |
| 09:30 | Individualized silica nanohelices and nanotubes: new substrates for Gold nanoparticles towards 3D SERS applications Authors : MH Delville, R. Tamoto, S Si, R. Oda, S Leconte Affiliations : CNRS/ICMCB, Université de Bordeaux France CBMN/IECB/CNRS Université de Bordeaux, France; Resume : We report that organic chiral nanometric ribbons of cationic gemini surfactants with tartrate counter-anion can be transcribed to inorganic nanostructures via the sol-gel polycondensation of tetraethylorthosilicate (TEOS) . The morphology of the inorganic nanostructures are controlled by various parameters such as temperature, concentration of different reactants, and more surprisingly, also by the kinetics of both organic assembly formation and inorganic polycondensation . In this study, we show that these silica helices functionalized with –NH3 groups can interact strongly with gold nanoparticles (GNP) of 1 ~ 2 nm diameter stabilized by tetrakis(hydroxymethyl)phosphonium chloride (THPC) and that they can be used as template to prepare hybrid nanohelices homogeneously coated with GNPs.
Interestingly, we observed the solvent controlled GNP growth on the surface of silica nanohelices: when the Silica helices/GNPs nanoobjects are kept in suspension in alcohol, the GNPs at the surface of silica helices tend to grow to around 5 ~6 nm with time indicating the mobile nature of GNP at silica surface, whereas this growth is not observed in water(figure). Thus, the GNPs size can be controlled at the surface of silica simply by solvent exchange. The detail of the growth kinetics is followed by UV and RAMAN spectroscopy. This provides a novel method for designing nanocomposites and opens a wide field for further photonic applications. | 4 18 |
| 09:45 | Fluorescent enhancement of ultrathin polymer layers for sensing applications. Authors : Roy AAD, Christophe COUTEAU, Laurent DIVAY, Christophe GALINDO, Pierre LE BARNY, Corinne SARTEL, Vincent SALLET, Gilles LERONDEL Affiliations : University of Technology of Troyes, University of Technology of Troyes, THALES, THALES, THALES, GEMaC, GEMaC, University of Technology of Troyes Resume : Fluorescence quenching of polymers have proved to be a promising process for sensing the presence of volatile chemical compounds. However, Fluorescence quenching faces some technical difficulties in order to enhance the sensing. Inevitably, Fast response times require the use of extremely thin films (< 20nm) in order to emphasize and homogenize the analyte diffusion throughout the whole polymer layer. Such extreme thinness weakens the light absorption and fluorescence intensities of the polymer layer which, in turn, gravely increase its detection threshold. In this context, we propose a new concept to enhance the absorption and fluorescence of ultrathin films. The concept consists of coating the ultrathin polymer layer on active waveguiding support. The hybrid organic-inorganic structure enhances the polymer fluorescence through an efficient energy transfer. Experimental results are presented considering the specific case of FSP coated on ZnO. The results are compared to standard FSP-quartz samples. FSP-ZnO samples showed an enhanced fluorescence. In addition, FSP-quartz and FSP-ZnO samples presented differing intensity dependencies. While FSP-quartz saturated under high pumping intensities, FSP-ZnO presented nonlinear intensity dependence. Experimental investigation showed the FSP-ZnO behavior to be the result of both an energy transfer between FSP and ZnO and a geometrical effect ensured by the waveguiding in the ZnO thin film. The obtained results prove the validity of the concept. | 4 19 |
| 10:00 | Coffee break | |
| 10:30 | Multifunctional superparamagnetic-plasmonic and -phosphorescent nanocomposite polymer films Authors : Georgios A. Sotiriou, Christoph O. Blattmann, Sotiris E. Pratsinis Affiliations : Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, ETH Zurich Resume : The synthesis of multi-layer polymer nanocomposite films with multifunctional filler particles was investigated here. The resulted films exhxibit the characteristic properties of each component, such as magnetic, plasmonic and phosphorescent [1]. The filler particles are homogeneously dispersed within the polymer films, allowing for uniform properties along the whole range of the film. Such structures are advantageous for several applications that require multiple functionalities such optical filters, biosensors, luminescent materials. Here, the magnetic and plasmonic performance of these polymer composites is demonstrated. Furthermore, free-standing microstructures can be made by depositing the polymer nanocomposite films on a sacrificial layer. The filler film stays intact after the addition of the polymer, resulting in high-filler-fraction polymer nanocomposites with uniquely homogeneous distribution. Such structures ideal for their integration in micro- and nano-fabrication techniques, for example fr the formation of superparamagnetic cantilevers.
References
[1] Sotiriou, G. A., Hirt, A. M., Lozach, P. Y., Teleki, A., Krumeich, F. & Pratsinis, S. E. Hybrid, silica-coated, Janus-like plasmonic-magnetic nanoparticles. Chem. Mater. 23, 1985-1992 (2011). | 5 20 |
| 10:45 | Experimental Observation and Analysis of Surface Second-Harmonic Generation from GaP Nanopillars Authors : Reza Sanatinia(1), Marcin Swillo(2), and Srinivasan Anand(1) Affiliations : (1) School of Information and Communication Technology, KTH Royal Institute of Technology, Electrum 229, S-164 40 Kista, Sweden (2) School of Engineering Sciences, KTH Royal Institute of Technology, S-106 91 Stockholm, Sweden Resume : Nonlinear optical response, e.g. second-harmonic generation (SHG), in nanowires could be of great interest as novel nanoscopic light sources and active nonlinear elements in future nanophotonic devices. In nanostructured materials, e.g., nanopillars (NP), the large surface to volume ratio can provide added benefit compared to bulk samples where surface SHG has traditionally been used as a probe to detect adsorption and orientation of single layers of organic molecules. For NP geometries the relative contribution of the bulk and surface effect may depend on the size of the wire. Thus coupling efficiency of the pump to the NPs and the intensity of SHG can be tailored by optimization of the diameter of the pillars. In this work we report on the experimental observation and analysis of SHG (at a wavelength of 420 nm) from vertically aligned GaP NPs fabricated via nanosphere lithography (NSL) and dry etching. We demonstrate a strong dependence of the SHG intensity on pillar diameter. The surface and bulk contributions to SHG from the pillars are analyzed, taking into account the calculated electric field profiles and coupling efficiencies. Complementary measurements of surface optical phonons by Raman spectroscopy were also performed and shown to be in agreement with the calculated field intensities at the surface. Finally, polarization of the measured light is used to distinguish between the bulk and surface SHG from GaP NPs. | 5 21 |
| 11:00 | Response properties of high efficiency photodetectors based on Ge nanoclusters Authors : S. Cosentino1,2,3, Pei Liu3, S. Mirabella2, I. Crupi2, Son T. Le3, M. Miritello2, S. Lee3, D. Paine3, A. Terrasi1,2, A. Zaslavsky3, D. Pacifici3 Affiliations : 1 Dipartimento di Fisica ed Astronomia, Università di Catania, ITALY ; 2 MATIS CNR-IMM, Catania, ITALY ; 3 School of Engineering, Brown University, Providence, RI 02912, USA Resume : Progress in semiconductor photonics requires circuits with highly integrated, fast and efficient photodetectors (PDs). Germanium nanostructures are gaining renewed interest as optically active materials because of their easier bandgap tuning via quantum confinement, compared to Si nanostructures, and their easy integration in Si technology. Moreover, the larger carrier mobilities and lower bandgap in Ge compared to Si are promising for the realization of fast optoelectronic devices operable at 1550 nm.
Recently, we have demonstrated simple high-efficiency MOS PDs where the active region is a thin film of densely-spaced amorphous Ge nanoclusters (NCs) embedded in SiO2. As a result of conduction mechanisms assisted by hole trapping in Ge NCs [1], our PDs show internal quantum efficiency up to 700% and responsivity up to 4 A/W, rivaling approaches based on Si or crystalline Ge NCs.
In this work, we study the role of structural properties (such as NC size and density, defect density at the Ge/SiO2 interface and NC structural phase) on the response of our PDs. Moreover, we report a detailed study on the response time of our Ge NC-based PDs, which falls below 1 usec, significantly faster than previously demonstrated Si NC-based PDs. Our results suggest that Ge NCs are promising for fast and high-performance integrated optoelectronic devices, fully compatible with Si technology in terms of fabrication and thermal budget.
[1] S. Cosentino et al., Appl. Phys. Lett. 98, 221107 (2011) | 5 22 |
| 11:15 | New organic-inorganic hybrid material based on vinyl ether function as an organic part, studied by 29Si-NMR spectroscopy: Applications to photonic devices fabrication Authors : S. Yaacoub, S. Calas, J. Jabbour, M. Abdallah, R. Tauk, P. Etienne, A. Khoury. Affiliations : (1)Charles Coulomb Laboratory, University of Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 05, France (2) Applied Physics Laboratory, Lebanese University, Campus Fanar- BP 90656- Jdeideh- Lebanon Resume : In the last few years, hybrid organic-inorganic materials were particularly attractive for integrated optics circuits fabrication. Mineral network is synthesized by sol-gel process and organic network is created by photopolymerization process via laser writing.
Previous works were based on a hybrid precursor [2-(3, 4 epoxycyclohexylethyltrimethoxysilane)] using cationic polymerization. The main advantage of cationic polymerization is its ability to allow cure reaction in the presence of oxygen, unlike radical polymerization. Results show high attenuations for the use of this material in integrated optic at 1550 nm which is mainly due to the presence of OH groups originating from the sol-gel process and the photopolymerization and more weakly to the presence of aliphatic CH groups.
The main objective of this work is to remove this difficulty by developing a new generation of hybrid materials with a very high reactivity and low amount of groups involved in the attenuation. We have choosen vinyl ether functions as an organic part because of their well known high polymerization rates via cationic way which are faster than the epoxide function and which lead to no OH groups generation and a very low aliphatic CH groups introduction.
Moreover, in the order to reduce the fabrication cost of devices, we propose to use a wavelength out of the UV field typically used. Thus, we develop a light- cured material in the blue (visible field). In this work hydrolysis and polycondensation of vinyl ether based solution are followed by liquid and solid Si-NMR. The main objective is to obtain the highest reactive multifunctional oligomer and the lowest OH groups. The effect of pH, hydrolysis rate and temperature are studied. We obtain 3D waveguides with a cross section 5×5 μm2 | 5 23 |
| 11:30 | Sub-bandgap formation in ZnO thin films with embedded Si quantum dots Authors : Kuang-Yang Kuo, Shu-Wei Hsu, Pin-Ruei Huang, Wen-Ling Chuang, Chuan-Cheng Liu, and Po-Tsung Lee Affiliations : Department of Photonics & Institute of Electro-Optical Engineering, National Chiao Tung University, Taiwan Resume : To realize the bandgap engineering of Si material, and simultaneously prevent the visible and near-infrared light absorption and reduce carriers’ transportation loss from matrix, we employ ZnO as the matrix material for nano-crystalline Si (nc-Si) quantum dots (QDs). We develop the nc-Si QDs embedded ZnO thin films utilizing a ZnO/Si multilayer (ML) structure by sputtering and a high-temperature annealing process for the high-crystallinity Si QDs formation. The ZnO/Si ML thin films show a high-density of amorphous Si nano-clusters after deposition and a high-crystallinity of Si QDs in the crystalline ZnO matrix after annealing at 1000°C. Though embedded with nc-Si QDs, the optical properties of ZnO thin film are still preserved in the long- and short-wavelength ranges. On the other hand, the significantly enhanced light absorption and an unusual photoluminescence peak contributed from nc-Si QDs are observed in the middle-wavelength range. Moreover, in addition to the wide optical bandgap of 3.34 eV from ZnO matrix, an optical sub-bandgap of 1.86 eV close to the unusual photoluminescence peak located at 1.81 eV is obtained. These results represent a meaningful sub-bandgap can form in ZnO thin film by integrating with nc-Si QDs while maintaining the essential and advantageous optical properties of ZnO matrix. We believe this novel composite material has great potential to enhance the performance of future optoelectronic devices with nc-Si QDs. | 5 24 |
| 11:45 | Quantum dot infrared photodetectors integrated on Si Authors : J.Frigerio, S.Bietti, S. Cecchi, G. Isella, S. Sanguinetti Affiliations : L-NESS Politecnico di Milano Polo Territoriale di Como via Anzani 42 22100 Como Italy; L-NESS Dip. di Scienza dei Materiali Università di Milano-Bicocca via Cozzi 53 Milano 20126 Italy; L-NESS Politecnico di Milano Polo Territoriale di Como via Anzani 42 22100 Como Italy; L-NESS Politecnico di Milano Polo Territoriale di Como via Anzani 42 22100 Como Italy; L-NESS Dip. di Scienza dei Materiali Università di Milano-Bicocca via Cozzi 53 Milano 20126 Italy Resume : Infrared (IR) imaging is extensively used in many technological fields, such as defence and medical diagnostics. Many research efforts are directed towards the fabrication of cheaper and more efficient IR detectors by integrating the sensing element on a silicon-based read-out integrated circuit and by increasing the temperature of operation. In this context we are developing a quantum dot infrared photodetector (QDIP) integrated on Si where GaAs quantum dots are embedded in an AlGaAs matrix deposited on a Ge-on-Si virtual substrate. Ge-on-Si epilayers are grown by low-energy plasma-enhanced CVD. The QDs are obtained by droplet epitaxy, a variant of MBE exhibiting several features relevant to our purposes, such as the low thermal budget and the wide tunability of QD density, dimension and shape. Multispectral acquisition is in principle possible using the Ge-on-Si layer as a p-i-n photodiode for absorption in the short wave IR and a QDIP for long wave IR detection. In the route towards the realization of a CMOS compatible IR photodetector we have developed a QDIP based on droplet epitaxy GaAs/AlGaAs strain free quantum dots at low thermal budget and the lithographic process for the fabrication of a QDIP device. Preliminary measurements on a QDIP fabricated directly on a GaAs substrate have shown extremely low dark current densities of 3×10-10 A/cm2 at 77 K and 5 × 10-8 A/cm2 at 300 K. These results confirm the high quality achievable by the developed fabrication process. | 5 25 |
| 12:00 | Lunch | |
| 13:30 | From Si to SiC nanostructures Authors : L. Latu-Romain, M. Ollivier, A. Mantoux, M. Martin, and T. Baron Affiliations : 1. Laboratoire des Technologies de la Microélectronique (UMR5129 CNRS-UJF),17 av des Martyrs 38054 Grenoble, France 2. CEA, LETI, MINATEC, 17 av des Martyrs 38054 Grenoble, France (1 and 2 for all authors) Resume : Among numerous materials, bulk silicon carbide is of great interest due to its superior physical and chemical properties: hardness, high thermal and chemical stability, biocompatibility, high breakdown electric field and electron drift velocity. It makes silicon carbide a material of choice for bio and gas-sensors. Moreover, the tremendous interest in nanoscale structures such as quantum dots (zero-dimension) and wires (quasi-one-dimension) stems from their size dependent properties. One-dimensional (1D) semiconductor nanostructures are of particular interest because of their potential applications in nanoscale electronic devices. Among various semiconductor materials, the growth of silicon nanowires has been extensively studied; however silicon has some disadvantages, it cannot be operated at high temperature, high power and high frequencies, and furthermore its biocompatibility and its chemical inertia is lower compare to silicon carbide. On another hand, the growth of SiC nanowires has been less studied, and the transport in silicon carbide nanowires keeps poor because of a low structural quality.
In this context, Si nanowires networks can be obtained, but there is still a real challenge for such structure to be inert versus gases and biology. We propose here to present how a continuous protective shell of silicon carbide could be grown from Si nanowires and provides this function.
By starting from single crystalline Si nanowires grown either by top-down or bottom-up approaches, silicon carbide has been obtained by carburization. The carburization is realized in a horizontal tube furnace at 1100°C during several minutes under methane diluted in hydrogen.
In a first study, all the nanowire has been carburized, and it leads to the transformation from Si nanowire into SiC nanotube. A model of growth based on the outdiffusion of Si through the SiC layer was proposed to explain the transformation from Si nanowires to SiC nanotubes. This model was completed with thermodynamic calculations on the Si–H2–CH4–O2 system.
In a second part, Si core /SiC shell nanowires have been elaborated. The pressure has been increased until atmospheric pressure and a very thin shell of silicon carbide has been grown all around the Si nanowires. In this case, the silicon carbide grown is cubic (3C-SiC) because of the growth temperature at 1100°C; the thickness varies from 2 nm to 4 nm depending on the carburization time. And finally, the silicon carbide layer is single crystalline and above all is continuous all around nanopillars. Original FIB-SEM preparation and TEM characterizations of these nano-objects will be presented.
Silicon carbide may be used as a protective shell; these new nanomaterials (SiC nanotubes or Si/SiC core/shell nanowires) offer new possibilities for nano-electronics, bio- and gas-sensors. | 6 26 |
| 13:45 | Highly tunable piezoelectrically actuated AlN-based coupled RF-resonators Authors : Nicola Heidrich (1), Fabian Knöbber (1,2), Wilfried Pletschen (1), Ram Ekwal Sah (1), Brian Raynor (1), Volker Cimalla (1), Oliver Ambacher (1,2), Vadim Lebedev (1) Affiliations : (1) Fraunhofer Institute for Applied Solid State Physics, Tullastraße 72, 79108 Freiburg, Germany (2) IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 70110 Freiburg, Germany Resume : Microelectromechanical systems as stable frequency references for radio frequency (RF) applications have potential advantages over commonly used devices such as quarz crystals and surface acoustic wave resonators due to their miniaturisation capability, high frequency performance and wide tuneability by more than 100%.
We report on complementary resonators made from piezoelectric AlN thin films designed to operate in flexural vibration modes. These devices are made from doubly clamped beams composed of two AlN-layers, actuation and elastic, separated by a thin metal electrode. A nano-gap of 80 – 200 nm created by focused ion beam forms two separate cantilevers.
Cantilevers of lengths from 5 to 125 µm were investigated in strongly coupled (normal) vibration modes realized by electrostatic coupling to achieve precise synchronization of oscillations for both resonators.
Here, the first normal mode is of particular interest, because two cantilevers evolve with a phase difference of 180°, resulting in the maximal distance between the cantilever tips. Selectively excited, the frequency can be tuned independently within a very wide frequency range by varying the electrostatic coupling between cantilevers.
The presented active tuning method adds a unique functionality to integrated MEMS components, offering great advantages for multi-band RF signal processing. | 6 27 |
| 14:00 | PDMS micromixers bonded to flexible polymeric films by application of oxygen plasma and amino-silane treatment Authors : Michael Lee (a)*, Maria J. Lopez-Martinez (b,c), Abdellatif Baraket (a), Nadia Zine (a), Jaume Esteve (c), Jose A. Plaza (c), Nicole Jaffrezic-Renault (a) and Abdelhamid Errachid (a)** Affiliations : (a) Laboratoire des Sciences Analytiques (LSA), Université de Claude Bernard-Lyon1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France. (b) Presently Department of Pharmacy, University of Groningen Antonius Deusinglaan 1, P.O. Box 196, 9700 AD Groningen, The Netherlands. (c) Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193, Bellaterra, Barcelona, Spain. *corresponding author: michael.lee@etu.univ-lyon1.fr **abdelhamid.errachid@univ-lyon1.fr Resume : Microfluidic systems investigate the fluidic flow of a substance through a microchannel that can incorporate actuators, filters, mixers, and pumps. Collectively, these components can complete a micro total analysis system (µTAS) that can process biological material using smaller volumes and reagents with reduced analysis times [1]. Standard microfluidic devices use a structured silicon mould that fabricates a replica poly(dimethylsiloxane) (PDMS) mould [2]. In general, the structured PDMS mould is plasma activated to adhere to glass or silicon based substrates. However, in recent years, microfluidic PDMS devices bonded to polymeric films [3-4] have drawn considerable attention within medical research due to its compelling properties of flexibility and biocompatibility.
Here, we describe a technique for the production of replica PDMS micromixers from a silicon mould [5] that were plasma treated to induce hydroxyl groups on the siloxane chain for polymer-polymer bonding. The thermoplastic films applied were: poly(ethylene naphthalate) (PEN), poly(ethylene terephthalate) (PET), and polyimide (PI). Activation of these films were made by incubation in (3-aminopropyl)triethoxysilane (APTES) (6%) diluted with Mill-Q ultra-pure water for 20 min. Upon adhesion, the polymer-polymer forms irreversible chemical bonds due to the formation of silanol groups, Si(OH)3.
Characterisation of these thermoplastic films by contact angle measurement (CAM) demonstrated a surface free energy of PI, 67.7mN/m; PEN, 69.7 mN/m and PET, 64.2 mN/m, that were similar to oxygen activated glass at 72.1 mN/m. X-ray photoelectron spectroscopy (XPS) analysis determined the elemental composition of these silanol induced thermoplastics and results concluded that Si(OH)3 bonds have been functionalized onto these polymer films by APTES activation.
To establish the application as a functional micromixer, two polar inks were injected into the PDMS micromixer adhered to PI. The PDMS micromixer consisted of 18 mixing loops along a total microchannel (‘C’ shaped) length of 6.05 mm and a width of 100 µm. The width of the mixing loops were 50µm, with the loop exit at 15 µm. The total depth was 70 µm. This passive micromixer creates turbulence flow that propels the two inks back into the main microchannel. This enhanced mixing efficiency ensured complete mixing of the two injected dyes and no apparent leakage was observed due to the strong affinity of polymer-polymer adhesion.
These devices will essentially analyse biological material, where incorporation of microfilters can aid in sample preparation, separation, and finally detection of the required response in µTAS.
Acknowledgement:
We acknowledge the funding through the Ministère de L’enseignement Supérieur et de la Recherche (MESR) and from the SensorART project, funded by the European Communities Seventh Framework Programme (FP7/2007-2013), under the grant agreement No. 248763, and by the Spanish Government through the MINAHE 3 project MEC-TEC2008-06883-CO3-01, and it reflects only the authors’ views.
References:
[1] C.A. Mills, E. Martinez, F. Bessueille, G. Villanueva, J. Bausells, J. Samitier and A. Errachid. Microelectron. Eng., (2005), 78-79, 695-700.
[2] Y. Xia, and G.M. Whitesides. Annu. Rev. Mater. Sci., (1998), 28, 153-184.
[3] K. Aran, L. A. Sasso, N. Kamdar and J. D. Zahn, Lab. Chip, (2010), 10, 548-552.
[4] L, Tang and N. Y. Lee, Lab. Chip, (2010), 10, 1274-1280.
[5] M. J. Lopez-Martinez, E. M. Campo, D. Caballero, E. Fernandez, A. Errachid, J. Esteve and J. A. Plaza, J. Micromech. Microeng. 2009, 19, DOI: 10.1088/0960-1317/19/10/105013. | 6 28 |
| 14:15 | Synthesis of nanofilms with dendritic grafts for biomolecules immobilisation Authors : Hakim RAHMA a, Karine HEUZÉ a, Luc VELLUTINI a, Manuel GABOYARD b, Bernard BENNETAU a Affiliations : a Université de Bordeaux, Institut des Sciences Moléculaires, UMR 5255-CNRS, 351 cours de la Libération, 33405 Talence Cedex, France. ; b Ademtech SA., Parc Scientifique Unitec, 4 Allée du Doyen Georges Brus Pessac, 33600, France. Resume : During lasts decades, there was a real demand to develop new methods for biological species analysis, because of the cost, the complexity and the large time of analysis of existing methods. Biosensors allow real time analysis in complex medium, it has a strong potential in the development of new analytical tools in the health field. However, the efficiency of biosensors depend on the interface chemistry between the solid support and species to be detected, such as in the case of controlled proteins immobilisation.
Recently, it has been shown that some biomolecules can be immobilized on silica SiO2 via organosilane coupling agent.[1] These Types of coupling agents RSiX3 (X=Cl or OCH3) react with silanol groups of silica surface to form covalent bon Si-O-Si. It has been also shown that they can organize themselves on the surface to form SAM (Self Assembled Monolayer). The aim of this work is to use dendritic poly(amidoamine) like coupling agents to multiply the number of potential sites to hang biomolecules.
In fact, one dendritic molecule grafted will generate several sites to grip on the surface support.[2] The grafting of these dendritic coupling agent is leads in parallel on flat surface of silica SiO2 (for biomolecules immobilization) and on magnetic nanoparticules core-shell coated with silica SiO2 (in collaboration with the company ADEMTECH, for applications in proteomics).
(1) D.H. Dinh et al., Langmuir 2009,25, 5526
(2) J. Bu et al., Macromolecules 2004,37, 6687 | 6 29 |
| 14:30 | Wet processing-based fabrication of self-assembling nanofibers arrays Authors : Alessandro Fraleoni-Morgera*, Ennio Capria, Giuseppina Palma Affiliations : Sincrotrone Trieste SCpA Resume : Wet processing methods can in principle allow large area depositions with low costs, rapidity, easiness of implementation, but approaches like self-assembling, contact printing or electrospinning, lack the ability to deliver features homogeneity over areas as large as thousands of micron2 in reasonable times and at acceptable costs. We report on a novel, fast, low-cost and versatile wet-processing method capable of producing large area, ordered arrays of filamentary nanostructures within minutes. The technique, named Auxiliary Solvent-Based Sublimation-Aided NanoStructuring (ASB-SANS), exploits an organic crystal able to sublimate (SS) as a templating matrix for the material to be structured/patterned (Target Material, TM) [1], and allows an extreme versatility in terms of patternable TMs. Examples of the outcome of ASB-SANS on organic polymers, carbon nanotubes (CNTs) or inorganic nanoparticles will be presented. The size of the obtained features, as well as the topology of the fabricated patterns, can be controlled varying the growth conditions and/or the SS/TM ratio in the starting solution. The possible applications of ASB-SANS to technologically relevant fields like organic electronics will be also presented.
Refs
[1] A. Fraleoni-Morgera, Small, 2011, 7, 321 | 6 30 |
| 14:45 | Dewetting-Driven Hierarchical Self-Assembly of Small Semiconductive Molecules Authors : Jean-Nicolas Tisserant (1,2), Roland Hany (1), Stefan Partel (3), Gian – Luca Bona (4), Raffaele Mezzenga (2) , Jakob Heier* (1) Affiliations : (1) Empa, Laboratory for Functional Polymers, 8600 Dübendorf, Switzerland (2) ETH Zürich, Department of Food and Soft Materials Science, 8092 Zürich, Switzerland (3) FH Vorarlberg, Research Center for Microtechnology, 6850 Dornbirn, Austria (4) EMPA, ETH Zürich, ETH Zürich, Department of Information Technology and Electrical Resume : We demonstrate a versatile method to fabricate thin films of organic semiconductive materials with sub-micrometer patterns by a simple coating process from solution. PCBM and a cyanine dye self-assemble via liquid-liquid dewetting during film formation. Here, we combine self-assembly with micro-contact printing [1] to organize these materials into a 1D or 2D photonic crystal lattice. Characteristic to the liquid-liquid dewetting process is that a PCBM top layer decomposes into lenses floating on the lower cyanine liquid surface during solvent evaporation. The lateral dimensions of these lenses in the final film show a linear dependence on the film thickness [2]. The underlying surface pattern adds degrees of freedom to the system, which allows for additional film morphologies engineering. We observe transitions from one wetting morphology regime to another, and the surface pattern can selectively be wetted and replicated when the system's characteristic decomposition wavelength matches with the pattern periodicity. Contact line pinning of the evaporating PCBM droplet onto the underlying substrate structure allows for control of pattern formation. Such photonic structures can enhance the light-matter interaction through "slow Bloch modes" in the material and are thus promising candidates for the improvement of light harvesting in organic photovoltaic devices [3].
[1] A. Kumar, G. M. Whitesides App. Phys. Lett. 1993, 63, 2002.
[2] J. Heier et al., Langmuir 2008, 24, 7316.
[3] D. Duché et al, Appl. Phys. Lett. 2008, 92, 193310. | 6 31 |
| 15:00 | Oligonucleotide solid-phase synthesis on fluorescent silica particles of nanometric size Authors : Gabriel De Crozals1, Carole Farre1, Christophe Marquette2, Céline Mandon2, Matteo Martini3, Jean-Jacques Toulmé4, Sonia Darocha4, Claire Billotey5, Marc Janier5, Laurence Marmuse6, Cédric Louis6, Carole Chaix1 Affiliations : 1Université de Lyon, UMR 5280 CNRS, ISA, France; 2Université de Lyon, UMR 5246 CNRS, ICBMS, France; 3Université de Lyon, UMR 5620 CNRS, LPCML, France; 4INSERM U869, Bordeaux, France; 5Médecine nucléaire, Hôpital E. Herriot, France; 6NANO-H S.A.S., Lyon, France Resume : In recent years, a growing interest has been devoted to the elaboration of nano-sized objects functionalized on surface by biomolecules for medical imaging, biosensors or therapeutics. The great potential of functionalized nanoparticles (NPs) led us to think about how to optimize the coupling of a complex biomolecule on a silica particle. Indeed, the formation of these conjugates is usually restricted by the coupling step because of problems of aggregation, purification and low yield.
In this context, we have developed an innovative silica material called NOM (nano-on-micro) support that allows oligonucleotide direct synthesis on the NPs immobilized on a micrometric support (Farre, Langmuir, 2010). We present the last improvements of the strategy that concerns first the nature of the micrometric silica support used for the NOM assembly and second, the use of fluorescent silica NPs as markers.
We have demonstrated that NOM are suitable for nucleic acid automated synthesis by standard chemistry. Both DNA probe and RNA aptamer were synthesized from the NP surface and binding assays performed in vitro have shown the ability of the conjugates for targeting complementary DNA strand and protein, respectively.
By this process, NPs can be derivatized with a wide range of functional blocks including fluorophores, targeting probes, PEG… This new approach offers the prospect of a multi-functionalization of NP easier, allowing numerous applications in the biomedical field. | 6 32 |
| 15:15 | Click chemistry and/or microwave irradiation for nanoparticle surface modification Authors : Erwann Guénina, Farah Benyettou, Yoann Lalatonne, Laurence Motte Affiliations : CSPBAT laboratory, UMR 7244 CNRS, University Paris 13, 74 rue Marcel Cachin, 93017 Bobigny, France Resume : Magnetic nanoparticles (mNPs) are attractive candidates for magnetic immunoassays, cell labelling, imaging (MRI), and mediators of therapeutic hyperthermia as well as nanovectors for drug and gene delivery.1 For all these applications mNPs will have to interact with other systems such as ligands, receptors, biomolecules, polymers. It is so crucial that mNPs surface have a define molecular structure. They must be surface functionalized with a precise control of quantities and orientation in order to meet the needs of specific applications.2 In this contribution we will describe two methods for the functionalization of superparamagnetics γ-Fe2O3 nanoparticles coated with various molecules of the hydroxymethylene bisphosphonic acids (HMBP) family.3,4 Depending on HMBP functionalities we will describe improvement of classical peptide bond formation by microwave6 as well as the uses of click chemistry approaches for the functionalization of these mNPs. These two approaches led to the obtaining of a controlled and efficient functionalization of mNPs.
References
1. N. Tran and T. J. Webster, J. Mater. Chem., 2010, 20, 8760-8767,
2. R. Nagarajan, In Nanoparticles: Synthesis, Stabilization, Passivation, and Functionalization, American Chemical Society, 2008, 996, 2-14.
3. Y. Lalatonne, C. Paris, J. M. Serfaty, P. Weinmann, M. Lecouvey, L. Motte, Chem. Comm. , 2008, 22, 2553-2555.
4. L. Motte, F. Benyettou, C. de Beaucorps, M. Lecouvey, I. Milesovic, Y. Lalatonne, Fara | 6 33 |
| 15:30 | Coffee break | |
| 16:00 | Sensing ammonia with surface ionization effects in SnO2 nanowires: new devices Authors : F. Shao1, F. Hernandez-Ramirez1,2, J.D. Prades2, A.Hacker3, G.Muller3, N. Lopez4, J.R. Morante1,2 Affiliations : 1. Catalonia Institute for Energy Research, IREC, Jardins de les Dones de Negre 1, 08930 Sant Adrià de Besòs, Barcelona, Spain 2. Department of Electronics, University of Barcelona, UB, Martí i Franquès 1, 08028 Barcelona, Spain 3. EADS Innovation Works Germany, EADS Deutschland GmbH, D-81663 München, Germany 4. Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007 Tarragona, Spain Resume : Surface ionization gas sensors based on individual SnO2 nanowires acting as main electrode, and its associated platinum counter electrode localized at 1,6 microns, in parallel and separated by a trench, have been developed for the measurement of NH3. These final devices exhibited robust characteristics and reproducible electrical responses in different experiments repeated along days. Provided that surface emission is enhanced with a high local electrical field in the range of 1MV/cm, the application of only few volts allows already having significant surface ionization current levels. Under these conditions, the electrons are injected in the metal oxide bulk material and transported to the counter electrode through the external circuit whereas the positive ions are transported to the counter electrode. Thus, the role played by the charge here is completely different of the role played in the conductometric measurements of metal oxide sensing materials. In this work, temperature and electrical field dependences have been analyzed showing that the application of a temperature of 250ºC and a few volts are enough for obtaining significant surface ionization currents. The analysis of the response time reveals its dependence on the NH3 concentration. This behavior is explained on the base of the required NH3 kinetic reactions and the corresponding formation of sub-products. All these characteristics constitute a clear advancement in the conception of new gas devices based on these transduction mechanisms that can be easily analyzed by using these individual nanowires as sensing platforms | 7 34 |
| 16:15 | Sensing water and alcohol vapors with freestanding silicon quantum dots Authors : R. Lockwood, J.G.C. Veinot, A. Meldrum Affiliations : Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada; Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada; Resume : An all-optical silicon-quantum-dot-based vapor sensor is described and demonstrated for the cases of atmospheric water and alcohols. The sensing mechanism employs the luminescence of free-standing silicon quantum dots prepared using a liquid-state chemical etch followed by dry-casting onto a clean silicon wafer. When the sample was exposed to the vapors of water, ethanol, methanol, isopropanol, butanol or butanediol in an oxygen carrier gas, the luminescence spectra of the silicon quantum dots evolved on the order of seconds to hours. An approximately 10-fold increase in the luminescence intensity was observed, with the rate of increase depending on the concentrations of the analyte vapor. Preliminary studies of consumer products were also examined: vapors from alcoholic beverages were tested and found to produce clear effects on the luminescence intensity. “Breath tests” were also conducted in which an experimenter breathed into an apparatus containing a quantum dot sample. The increase in the luminescence intensity is coincident with the formation of Si-O and Si-OH bonds on the surface of the hydride terminated Si quantum dots, as determined by Fourier transform infrared spectroscopy and consistent with photoluminescence lifetime spectroscopy. | 7 35 |
| 16:30 | Cobalt ferrite, a new gas sensing material Authors : Ch. Leroux1, M.Bendahan2, L.Ajroudi3, V.Madigou1, N.Mliki3 Affiliations : 1 IM2NP UMR CNRS 6242 Université Sud Toulon Var, BP20132, 83957 La Garde Cedex, France 2 IM2NP UMR CNRS 6242, Aix Marseille Université, Av.Escadrille Normandie Niemen, case 152,13397 Marseille Cedex, France 3 LMOP, Faculté des Sciences de Tunis, Université Tunis El Manar, 2090 Tunis, Tunisie Resume : We developed a one pot solvothermal route and produced well dispersed highly crystalline cobalt ferrites CoxFe3-xO4 nanoparticles with tailored size and various cobalt contents. We investigated the catalytic and electrical response of cobalt ferrite nanopowders in presence of gas. Catalytic tests were performed, by analyzing the outgoing gases by Infra Red Fourier Transform Spectrometry. We showed that the absorption peak of CO2 could directly be linked to the conversion rate of CH4 into CO2. These catalytic tests showed that the cobalt ferrite powder with x=1.8 had the best behaviour in presence of methane (highest conversion rate, lowest activation energy).
In order to test the electrical response of cobalt ferrite in presence of gas, the nanopowder were dispersed in terpineol, and a few drops were deposited of a Si substrate 5mmx5mm, with interdigitated Pt electrodes. Nanoparticles of Co1.8Fe1.2O4 and Co1Fe2O4 were tested in presence of reducing gases. Cobalt ferrite Co1.8Fe1.2O4 exhibits a classical electrical behaviour of semi conducting material in presence of reducing gases; the increase of resistance shows the cobalt ferrite with high amount of cobalt (x=1.8) is a p-type semi conductor. Alternatively, cobalt ferrite Co1Fe2O4 showed n-type semi conductor behaviour in presence of CO. The fast responses of these devices to low amount of gas are new promising results for the use of cobalt ferrites as gas sensing materials. | 7 36 |
| 16:45 | Experimental and theoretical studies of the NH3 interactions on SnO2 nanowire surfaces for new gas sensing devices. Authors : F. Shao1, F. Hernandez-Ramirez1,2, J.D. Prades2, T. Fischer3, S. Mathur3, N. Lopez4 J.R. Morante1,2 Affiliations : F. Shao1, F. Hernandez-Ramirez1,2, J.D. Prades2, T. Fischer3, S. Mathur3, N. Lopez4 J.R. Morante1,2 1. Catalonia Institute for Energy Research, IREC, Jardins de les Dones de Negre 1, 08930 Sant Adrià de Besòs, Barcelona, Spain 2. Department of Electronics, University of Barcelona, UB, Martí i Franquès 1, 08028 Barcelona, Spain 3. Institute of Inorganic Chemistry, University of Cologne, 50939 Cologne, Spain 4. Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007 Tarragona, Spain Resume : From long time ago, metal oxides in form of thick or thin films have been used to monitor the presence of NH3, and since then, significant progress has been made both in terms of fundamental understanding of the gas-metal oxide interactions as well as on the technological development of devices .To date, quasi-one-dimensional (1D) crystalline metal oxides nanostructures, such as nanowires and nanotubes, have shown promising features for gas sensing. They also offer unique properties to carry out fundamental studies, such as well-defined geometry and lack of grain boundaries inside, that facilitate the understanding of the gas-metal oxide sensing mechanisms. In this work, we report on the prototyping of individual SnO2 nanowire devices and the study of their NH3 sensing characteristics. Confronting experimental data with ab-initial DFT simulations, the main NH3-SnO2 interactions were identified. On the whole, our results show that nanoscale devices are a useful tool to gain a deeper insight in the properties of metal oxides. Making use of these intrinsic advantages of nanoscale prototypes, the analysis of the nanowires’ resistance modulation upon exposure to gas and their dynamic response, as function of temperature and gas concentration, allowed delimiting the main NH3-SnO2 sensing pathways, which is a must for real-time detection of NH3 in environmental monitoring and industrial applications. | 7 37 |
| 17:00 | Synthesis of Au-Pd Bimetallic Nanostructures and Their Electrocatalytic Activity Authors : Do Youb Kim, Kyeong Woo Choi, Xiao-Lan Zhong, Zhi-Yuan Li, Sang Hyuk Im, O Ok Park Affiliations : Dept. of Chem. Biomol. Eng., KAIST, Korea; Dept. of Chem. Biomol. Eng., KAIST, Korea; Inst. of Phys., CAS, China; Inst. of Phys., CAS, China; KRICT-EPFL Global Research Lab., KRICT, Korea; Dept. of Chem. Biomol. Eng., KAIST and Dept. of Energy Sys. Eng., DGIST, Korea Resume : In this presentation, we report a facile seeded growth for the synthesis of uniform Au-Pd bimetallic nanostructures with cubic and dendritic shapes and their electrocatalytic activities toward formic acid oxidation. Starting from single-crystal seeds of Au spheres with a uniform size, we could reproducibly obtain Au-Pd core-shell nanocubes and Au-Pd dendrites with narrow size distributions and in high yields. The shape of resultant Au-Pd nanostructures could be easily controlled by using different capping agents; cetyltrimethylammonium bromide (CTAB) for the Au@Pd core-shell nanocubes, and cetylpyridinium chloride (CPC) for the Au-Pd dendrites. Moreover, morphologies of resultant Au-Pd nanostructures could be readily controlled by varying the concentration of precursors, the amount of seeds, or both. We have also investigated their optical properties, as well as electrocatalytic activity for formic acid oxidation. | P1 1 |
| 17:00 | Electrical and Photosensing Characteristics of Al0.2Ga0.8As/In0.2Ga0.8As pHEMTs with A Transparent AZO Gate Authors : C. S Lee, W. C. Hsu, H. S. Hsu, Y. H. Liao, L. Y. Tseng, C. S. Ho, B. Y. Chou, H. Y. Liu, Y. N. Lai, E L. Huang, Y. B. Liao, E. P. Yao, F. C. Liao, and W. F. Lai Affiliations : Department of Electronic Engineering, Feng Chia University, 100, Wenhwa Road, Taichung, Taiwan 40724, R.O.C. Resume : Transparent Al-doped ZnO (AZO)-gated Al0.2Ga0.8As/In0.2Ga0.8As pseudomorphic high electron mobility transistors (pHEMTs) have been comprehensively investigated. The schematic device structure of the studied AZO-gated HEMT (AZO-HEMT) and a conventional Au-gated HEMT (Au-HEMT) upon the same epitaxial structure are grown by the MBE system. Upon the (100)-oriented semi-insulating (S. I.) GaAs substrate, epitaxial layers include sequentially a 5000 Å undoped GaAs buffer, a two-period undoped 500 Å Al0.22Ga0.78As/500 Å GaAs composite buffer, an inverted Si -doping of 1 1012 cm-2, a 50 Å undoped Al0.2Ga0.8As spacer, a 150 Å undoped In0.2Ga0.8As channel, a 50 Å undoped Al0.2Ga0.8As spacer, an upper Si -doping of 4 1012 cm-2, a 800 Å n-Al0.2Ga0.8As (3 1017 cm-3) barrier layer, and a 100 Å n+-In0.01Ga0.99As (3 1018 cm-3) cap layer. And the electron mobility (μn) and the two-dimensional electron gas (2DEG) concentration (n2DEG), characterized by the Hall measurements under a magnetic field of 5000 G, are 3850 cm2/V-s and 3.99 1012 cm-2 at 300 K.
For the device fabrications, mesa isolation was formed for both samples by wet-etching down to the substrate with the etching solution of H3PO4：H2O2：H2O = 1：1：30. Composite alloys of 750 Å AuGe/350 Å Au were evaporated upon the In0.01Ga0.99As cap layer and then were sintered by using the rapid thermal annealing (RTA) technique to form source/drain ohmic contacts. Before gate deposition, both samples were immersed into etching solutions of H3PO4 : H2O2 : H2O = 1 : 1 : 30 at the same time to leave 400 Å thick Al0.2Ga0.8As Schottky contact layer. For the Au-HEMT, an 800 Å Au-gate was evaporated on the gate recessed barrier layer. On the other hand, a 1100 Å AZO-gate was deposited by using a RF reactive magnetron sputtering system. The AZO target was prepared by mixing 99.99% ZnO and Al2O3 powders with the weight percentage ratio of 98 : 2. The target-substrate distance, deposition power, chamber pressure, and deposition rate were set to be 30 mm, 15 W, 1 mtorr, and 1.33 nm/min, respectively. The gate dimensions are 1 × 100 μm2 for both devices, and the gate-drain/source spacing is 7 µm.
For temperature-dependent device characteristics, the temperature-dependent two-terminal gate-drain current-voltage (IGD-VGD) characteristics of AZO-HEMT and Au-HEMT at 300K-450 K, measured by using a Keithley 4200 analyzer. The gate-drain breakdown voltage (BVGD) and forward turn-on voltage (Von) are defined at | IGD | = 1 mA/mm. Consequently, BVGD/Von of AZO (Au)-HEMT were determined to be -63/3.4 (-13.4/1.2) V, -39.8/3.6 (-11.4/0.8) V, -33.8/3.5 (-9.8/1.0) V, -43.2/3.6 (-10.2/1.0) V, -50.2/3.4 (-10.4/1.0) V, and -56.4/3.4 (-12.4/1.0) V at 300 K, 330 K, 360 K, 390 K, 420 K, and 450 K, respectively. Improved BVGD and Von characteristics of AZO-HEMT as compared to Au-HEMT are mainly attributed the intrinsic good insulating property of the ZnO to effectively suppress the gate leakages. Besides, both AZO-HEMT and Au-HEMT have exhibited superior thermal BVGD (əBVGD/əT)/Von (əVon/əT) coefficients of 44/0 mV/K and 6.67/-1.33 mV/K. Excellent əBVGD/əT and əVon/əT characteristics are partly due to wide energy-gap property of the Schottky contact layer to reduce the thermally-generated carriers by band-to-band transition. the extracted temperature-dependent BVGD and Von characteristics of the studied devices can observe BVGD values in both devices increased as the ambient temperature was increased from 300 K to 360 K, and then, on the contrast, decreased as the temperature was further increased from 360 K to 450 K. Both devices showed different əBVGD/əT polarities as compared to the monotonous increase of BVGD with temperature. The observed positive əBVGD/əT dependence at 300 K-360 K is believed to be due to the enhanced thermionic-emission mechanism as the Schottky barrier height was decreased with temperature. Therefore, reverse-biased gate leakages were enhanced to deteriorate the gate-drain isolation property at increased temperatures. Nevertheless, as the ambient temperature was further increased above 360 K, lattice scattering and carrier-carrier scattering mechanisms became dominant in the InGaAs channel to significantly degrade the electron transport properties. Both of the average electron velocity and gate-drain leakages were decreased. Therefore, both AZO-HEMT and Au-HEMT showed negative əBVGD/əT dependence at 360 K-450 K. The switching of dominant mechanisms in BVGD characteristics at high temperatures has led to the observed different əBVGD/əT polarities. This also minimized the differences in BVGD values between at 300 K and at 450 K to contribute superior əBVGD/əT coefficients in both devices.
For common-source of current-voltage characteristics of the studied AZO-HEMT and Au-HEMT at different temperatures ranging from 300 K to 450 K. The applied gate-source bias was set from 0.5 V to -2 V with VGS = −0.5 V/step. Both devices have shown good pinch-off behaviors. It is because the devised AlGaAs/GaAs composite buffer can effectively reduce the substrate leakages, and the AlGaAs/InGaAs/AlGaAs quantum well structure provides good carrier confinement capability. At VDS = 3 V, the maximum gm (gm, max) and IDS density at zero gate bias (IDSS0) for the studied AZO (Au)-HEMT are 137 (140) mS/mm/220.4 (210.5) mA, 134 (128) mS/mm/214.8 (197.7) mA, 125 (118) mS/mm/209.4 (190.7) mA, 120 (110) mS/mm/200.7 (180.7) mA, 113 (105) mS/mm/196.5 (174.5) mA, and 107 (101) mS/mm/189.4 (167.3) mA at 300 K, 330 K, 360 K, 390 K, 420 K, and 450 K, respectively. The present AZO-HEMT has shown comparable gm,max performance at 300 K, as compared to Au-HEMT. Nevertheless, gm,max values of AZO-HEMT are higher than those of Au-HEMT at higher temperatures. It is believed to be due to that increased ambient temperatures improved the conductivity in AZO-gate electrode. Therefore, that the AZO-gate modulation capability was improved to enable higher gm, max performance than those of Au-HEMT at high temperatures. The AZO-HEMT has also shown superior GVS variation of only -4.2% from 300 K to 450 K, as compared to -10.9% of Au-HEMT. Improved gm,max and GVS characteristics at high temperatures of AZO-HEMT are advantageous to high-temperature, high-linearity voltage gain performance, which will be discussed later. Besides, the threshold voltage (Vth) values of AZO (Au)-HEMT were determined to be -1.902 (-1.5333)/-2.03 (-1.598)/-2.082 (-1.662)/-2.124 (-1.702)/-2.168 (-1.751)/-2.172 (-1.84) V at 300/330/360/390/420/450 K, respectively. The extracted temperature-dependent Vth, gm,max, and GVS characteristics for AZO-HEMT and Au-HEMT can further calculate thermal threshold coefficient (əVth/əT), thermal GVS coefficient (əGVS/əT), and thermal gm,max coefficient (əgm,max/əT) of AZO-HEMT to be -1.8 mV/K, -0.33 mV/K, and -0.2 mS/mm-K, which have shown less variation than -2.05 mV/K, -0.73 mV/K, and -0.26 mS/mm-K of Au-HEMT. Improved high-temperature stability in thermal threshold, transconductance gain, and GVS linearity characteristics of AZO-HEMT are beneficial to high temperature and high linearity circuit operations.
For temperature-dependent intrinsic voltage gain (AV), and corresponding gm, and output conductance (gd) characteristics of AZO-HEMT and Au-HEMT at 300 K-450 K. The bias conditions of AZO (Au)-HEMT are VGS = -1.5 (-1.0) V and VDS = 3 V to obtain the maximum AV characteristic. The gm/gd values of AZO (Au)-HEMT were determined to be 133.5/0.52 (135.5/0.63), 130.4/0.53 (126.1/0.64), 124.8/0.55 (115.8/0.67), 120/0.58 (108.2/0.71), 110/0.6 (102.2/0.74), and 107/0.61 (98.6/0.78) mS/mm/mS/mm at 300 K, 330 K, 360 K, 390 K, 420 K, and 450 K, respectively. In both devices, gm/gd showed monotonously decreasing/increasing dependences with the increased temperature. It is because that the thermally-generated carriers will enhance gate/substrate leakages and, therefore, tends to deteriorating both gm and gd characteristics at high temperatures. The resultant AV values, defined as gm/gd, of AZO-HEMT were calculated to be 257/246/227/207/183/176 at 300/330/360/390/420/450 K, which have shown all superior characteristics to 214/197/173/152/138/126 of Au-HEMT. It is mainly because the improved gd characteristic is down to the required VGS to obtain gm,max for the AZO-HEMT with a lower Schottky barrier height than Au-HEMT. Besides, the present AZO-HEMT has also shown about 20.1 % and 39.7 % improvements in AV performance at 300 K and 450 K, respectively, as compared to the Au-HEMT.
For photoelectric characteristics of the devices, the IDS-VDS characteristics of AZO-HEMT and Au-HEMT in the dark and under illumination of white light with the incident optical power (Popt) of 13 dBm at room-temperature. The present AZO-HEMT has shown three-terminal tunable photosensing capability with R = 0.1/0.11/0.13/0.16/0.13/0.01 A/W at VGS = 0.5/0/-0.5/-1/-1.5/-2 V and VDS = 3 V, with the corresponding Iph values of 2/2.2/2.5/3.1/2.5/0.2 mA, respectively. Besides, Vth values of the AZO-HEMT before/under illumination are -1.9/-2.13 V. Iph can be calculated to be 3.07 mA. At room-temperature, IDS-VDS characteristics of the studied AZO-HEMT in the dark and under different incident wavelengths of 632 nm (red-light) and 980 nm (near-infrared), respectively. The measured IDSS0 values of the studied AZO-HEMT biased at VDS = 3 V are 268 mA/mm and 295 mA/mm under illumination of 632 nm and 980 nm wavelengths, respectively. The corresponding Iph values are 4.8 mA/mm and 7.5 mA/mm, and the corresponding R values are determined to be 0.24 W/A and 0.75 A/W. Consequently, higher photocurrent and higher responsivity of 980 nm light were observed than those of the 632 nm illumination for the present AZO-HEMT.
In summary, a transparent AZO-gated double δ-doped Al0.2Ga0.8As/In0.2Ga0.8As pHEMT sensor demonstrating superior temperature-dependent characteristics at 300 K-450 K and three-terminal voltage-tunable photosensing capability have been comprehensively investigated in this work. Improved high-temperature GVS linearity, voltage gain, and excellent thermal threshold stability performances have been achieved in the present AZO-HEMT as compared to a conventional Au-HEMT structure. In addition, high transmittances of 82%~98% for incident energy within 1.24 eV~3.54 eV obtained in the AZO electrode are beneficial to optical responsivity characteristics of AZO-pHEMT sensor. Photosensing behaviors with respect to different incident radiations of white light, red light (632 nm), or near-infrared (980 nm) were also studied. Photovoltaic effect was found to be responsible for the three-terminal optical sensing characteristics through experimental/theoretical verifications. Consequently, the present pHEMT with a direct formation of a transparent AZO gate is advantageous to OEIC or fiber-optic communication receiver applications. | P1 2 |
| 17:00 | Nanoscale growth morphology of Ag/SiC Schottky diodes Authors : F. Ruffino, M. G. Grimaldi Affiliations : F. Ruffino, M. G. Grimaldi Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, I-95123 Catania, Italy MATIS IMM-CNR via S. Sofia 64, I-95123 Catania, Italy Resume : Electrical transport across metal-semiconductor contacts is of great technological importance since they are used in electronics, optoelectronics, microwave devices, solar cells. The perfection of the Schottky interface plays an important role on the device characteristics. In particular, the morphology of metal films deposited on semiconductor substrates can determine the electrical performance of the Schottky diode. We present a study of the growth of sputtered Ag films on SiC by the atomic force microscopy technique. We analyzed the Ag film morphology as a function of the deposition parameters (time t and ionic current I) observing that the Ag grows initially as three-dimensional nanoclusters (NCs). Then the Ag film morphology evolves from NCs to partially coalesced structures, followed by a percolation morphology and finally to a continuous and rough film. Using consolidated theoretical frameworks and fitting approaches, the relations between morphology critical parameters (size and density of the Ag NCs) and the process parameters t and I were established: the application of the interrupted coalescence model allowed us to evaluate the critical mean islands diameter for the partial coalescence process; the dynamic scaling theories of growing interfaces lead, instead, to the determination of the dynamic scaling, growth, and roughness exponents; the study of the evolution of the fraction of covered area by the Ag islands allowed us the evaluation of the Avrami exponent. | P1 3 |
| 17:00 | Oblique sputtering depositions to control the nanoscale film roughening: the case of Ag on mica Authors : F. Ruffino, M. G. Grimaldi Affiliations : F. Ruffino, M. G. Grimaldi Dipartimento di Fisica e Astronomia and CNR-IMM MATIS, Università di Catania, via S. Sofia 64, I-95123 Catania, Italy Resume : Oblique deposition is a vapour deposition technique in which the incident atomic flux impinges the substrate from an oblique angle α enhancing atomic shadowing creating an inclined columnar film nanostructure. By controlling α uniquely shaped nanostructures can be produced: nanopillars, zigzag columns, spirals, slanted posts, and branched nanocolumns. They find applications in photonic crystals, magnetic storage devices, field emitters, pressure sensors, and optical sensors. Recently, an interesting phenomenon for the growth of thin film by oblique angle deposition was observed: the change of the film roughness σ with α. The wide-range control of σ is a key issue for technological applications ranging from micro- and nanoelectronics, to plasmonics, and biology. In this work, we present a study about the evolution of σ for thin Ag films sputter-deposited on mica as a function of α in the absence of strong shadowing effects (0°α48°). σ increases from 1.9 to 10.2 nm when α increases from 0° to 48° and this kinetic roughening is justified on the basis of geometric factors allowing to conclude that σσ0+ΔD•sinα, being σ(0)=σ0, and ΔD the standard deviation on the Ag nanocolumn mean size | P1 4 |
| 17:00 | N-doped zinc oxide nanoparticles Authors : Isabelle Trenque, Etienne Duguet, Stéphane Mornet, Manuel Gaudon Affiliations : All authors Université de Bordeaux, ICMCB CNRS-UPR9048 Resume : Colloidal n-doped zinc oxide nanoparticles (NPs) are receiving attention to their novel opto-electronic properties with applications as transparent thermal barriers for smart windows, dye-sensitized solar cells or transparent conducting films.1-3 Whatever the application, one important goal is to get NPs-based inks with high transparency in the visible range. Two ways of optimization can be distinguished: (i) optimizing the print ink formulation: NPs dispersion with prevention of aggregation; (ii) optimizing the NPs transparency. We investigated both routes: (i) a low-cost one-pot strategy consisting of the direct preparation of nanocrystals of n-doped ZnO (with Al3+, Ga3+, In3+ dopants) by forced hydrolysis in a non oxidative polyol is explored ; (ii) the encapsulation of each single NPs by a low refractive-index shell (as MgF2, ZnF2 or SiO2) serving as a self-supported anti-reflecting layer.
1 M. Shim, P. Guyot-Sionnest, Nature, 2001, 407, 981-983.
2 G. Garcia, R. Buonsati, [… ], D. Milliron, NanoLetters, 2001, 11, 4415-4420.
3 H. Serier, M. Gaudon, M. Ménétrier, Solid State Science, 2009, 11, 1192-1197. | P1 5 |
| 17:00 | Single Crystalline IrxRu1-xO2 Nanowires Authors : Yumin Lee, Sung Hee Chun, Hae-Young Shin, Jaeyeon Lee, Seokhyun Yoon, Myung Hwa Kim* Affiliations : Department of Chemistry & Nano Science, Ewha Womans University Resume : The mixed oxide of IrxRu1−xO2 is well known as one of high performance electrocatalysts due to its excellent stability as well as superior catalytic activity. We here present a facial synthesis of 1-dimensional metallic mixed oxide of IrxRu1−xO2 via a simple physical vapor transport process by controlling relative ratios of two precursors, RuO2 and IrO2, respectively. Also, we carefully characterized Raman spectra of a single IrxRu1−xO2 nanowires with variable contents of x using excitation laser sources with wavelengths of 488 nm and 632.8 nm in order to explore stoichiometric information of ternary mixed oxide nanowires. We observed that an Eg phonon mode of an IrxRu1−xO2 nanowire is being blue-shifted linearly with respect to the Ir contents. We could use our observation of frequency shift of the Eg phonon to determine stoichiometry information of nanowires which we also measured and confirmed by using EDS. From the shape of the phonon modes we measured, we could get information regarding crystalline quality that was also measured by HRTEM. | P1 6 |
| 17:00 | A novel growth morphology of nanoscale Au films on mica deposited by radio-frequency sputtering Authors : F. Ruffino, V. Torrisi, G. Marletta, M. G. Grimaldi Affiliations : F. Ruffino, M. G. Grimaldi Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, I-95123 Catania, Italy MATIS IMM-CNR via S. Sofia 64, I-95123 Catania, Italy V. Torrisi, G. Marletta Laboratory for Molecular Surface and Nanotechnology (LAMSUN), Department of Chemical Sciences- University of Catania and CSGI, Viale A. Doria 6, I-95125, Catania Resume : The study of the morphology of Au deposited on mica is crucial for the fabrication of flat Au films for applications in biological, electronic, optical devices. The understanding of the kinetic growth mechanisms of Au on mica allows to tune the process parameters (substrate temperature, pressure, rate deposition, film thickness) to obtain ultra-flat Au film as platform for anchoring self-assembling monolayers, molecules, nanotubes, nanoparticles. Obviously, the control of the kinetic growth mechanisms of Au on mica is a prerequisite for control of the film nano- and micro-structure to obtain materials with desired morphological properties. While the main literature concerns Au film on mica produced by ultra-high-vacuum evaporation, in the present work we report a study of the morphology evolution of Au deposited on mica by RF sputtering with the film thickness h. We observed that the growth of the film starts by nucleation of Au nanoclusters (NCs) on the mica surface. This stage is complete for h=1.71017 Au/cm2. Then, the growth of the NCs occurs by ripening and/or coalescence processes. For h>1.71017 Au/cm2 a new phenomenon is observed which has no analogous for evaporated Au film on mica: the growth of microclusters formed by the aggregation of Au NCs, whose height increases and surface density decreases when h increases, following a coalescence/impingement dynamic. This phenomenon is linked, by quantitative evaluations, to the features of the sputtering technique. | P1 7 |
| 17:00 | NanoFETs with Optimal Sensitivity Considering the Statistical Performance Fluctuations Authors : Ming-Pei Lu,1 Cheng-Yun Hsiao,2 Wen-Tsan Lai,2 Yuh-Shyong Yang2 Affiliations : 1. National Nano Device Laboratories, Hsinchu 300, Taiwan; 2. Institute of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan Resume : Over the last decade, nanowire-based (NW) devices are of interest for the potential applications of the highly sensitive biological and chemical biosensors [1-4]. Recently, the improved sensitivity of NW biosensor in the subthreshold regime had been experimentally observed [5]. However, the significant statistical fluctuation in the electrical performance of NW devices is the crucial issue for reliably operating all NW devices at their optimized sensitivity; it will limit the practical applications of NW devices to the highly sensitive diseases diagnosis area.
A non-destructive method for evaluating the sensitivity of the liquid-gate nanowire-based (NW) biosensors has been demonstrated to suppress the impact of the statistical performance fluctuations on the sensitivity performance of NW biosensors. Thereby, the NW biosensor can be operated at its highest sensitivity by applying an appropriate liquid-gate voltage for the detection of the biomolecules at ultra-low concentration (~fM).
[1] Cui, Y. et al., Science, 293, p. 1289, 2001. [2] Li, Z. et al., Nano Lett., 4, p. 245, 2004. [3] Patolsly, F. et al., Nanomedicine, 1, p. 51, 2006. [4] Patolsky, F. et al., PNAS, 101, p. 14017,2004. [5] Gao, X. P. et al, Nano Lett., 10, p. 547, 2010. | P1 8 |
| 17:00 | A CMOS-compatible Process of Germanium Nano-wires Using Electron-beam Lithography Exposure of Hydrogen Silsesquioxane Resist Authors : Ran Yu*, Samaresh Das , Isabelle Ferain, Richard Hobbs, Yordan Georgiev, Pedram Razavi, Nima Dehdashti Akhavan, Cynthia A. Colinge and Jean-Pierre Colinge Affiliations : Tyndall National Institute Resume : We demonstrate a CMOS-compatible fabrication process suitable for patterning sub-40-nm width germanium nano-wires. This process relies on the integration of HSQ resist and fluorine-based etch chemistries. It allows for excellent nano-wire profile control and preserves the surface roughness of germanium, which makes that process suitable for integration within conventional top-down transistor process flows. Adherence between the HSQ layer and the germanium substrate is ensured by the deposition of a hard mask. Control of the nano-wire width and integrity is insured by a two-step pattern transfer, from the HSQ resist to the hard-mask first, and from the hard-mask to the germanium. Advanced imaging techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and high-resolution Transmission Electron Microscopy (HR-TEM) have been used to assess the nano-wires dimensions, germanium surface cleanliness (and its compatibility with further CMOS processing) and nano-wire profile, respectively. The sub-40-nm width germanium nano-wires have been further narrowed by thermal oxidation. After HSQ resist and hardmask removal, a straight profile for the germanium nano-wire is maintained up to a 50 nm depth. The hard-mask and patterning process have been selected in such a way that the fabrication of nano-wires can be achieved on bulk germanium or germanium-on-insulator substrates. | P1 9 |
| 17:00 | Nanoscale Materials (Nanocomposites, Nanowires, Carbon Nanotubes): Computational Modeling and Applications in Molecular, Cell Biology and Nanomedicine Authors : Katya Marinova Simeonova, Ganka Marinova Milanova Affiliations : Institute of Mechanics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria University of Architecture, Civil Engineering and Geodesy, 1000 Sofia, Bulgaria Resume : Discovering of carbon nanotubes (CNTs), by S. Iijima, [1] in 1991 was a revolution in nanoscience. (CNTs) possess extraordinary physico-mechanical properties, and could be used as reinforcement for nanocomposites (a matrix- polymer, ceramic etc. reinforced by CNTs). The aim of the work, presented could be formulated as follows: to give some basic studies, regarding to the mechanical behaviour of nanocomposites, and to discuss computational modeling of their properties. Nanowires, as nanoscale materials also have very important applications, as field effect transistor (NWFET), for example [2]. Some computational models, based on the classical mechanics theories and molecular dynamics for simulations of physico-mechanical, electronics, optical etc. properties of polymeric nanocomposites have been presented as well in the paper. Computational modelling by numerical author’s FORTRAN programs has been given too. Comparison between numerical results, obtained and experiments in literature shows a very good agreement. Applications of nanotubes, nanowires, nanorods, nanoparticles, nanodots, nanocomposites in engineering, technique, nanomedicine, molecular and cellular biology have been given, accounting for work [3]
References
1. S. Iijima, Nature, 1991, Volume 395, p.13
2. K. M. Simeonova, G. M. Milanova, ISCOM2007, 24-30 September 2007, Book of Abstracts, Peniscola, Spain, poster 123, page 136, (Grant from ISCOM2007)
3. . Simeonova K.M., Book Chapter1. 1. Simeonova K.M., Book Chapter: Cancer Research, Molecular and Cell Biology: Look at the Nanotechnology, Based Nanoparticles for Diagnostics, and Therapy. Stem Cell for Treatment of Cancer Diseases, ESACT Proceedings, SPRINGER, vol. 5 ,Jenkins, Nigel; Barron, Niall; Alves, Paula (Eds.),No. 2, pp.213-218 (2011). (ISBN 978-94-007-0883-9, IF=3.03) | P1 10 |
| 17:00 | Composite nanostructures based on a layered semiconductor with nanoscale 3D ferroelectric inclusions (p-GaSe intercalated by KNO3) Authors : A.P. Bakhtinov, V.N. Vodopyanov, Z. R. Kudrynskyi, V.V. Netyaga Affiliations : Chernivtsi Department of Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine Resume : In the present paper, impedance spectra of the composite nanostructures (p-GaSe intercalated by KNO3 ) are studied. The structures are composed of the GaSe crystalline layered semiconductor matrix, which contains 3D nanoscale pyramidal ferroelectric inclusions arranged along the C symmetry axis of the hexagonal crystal. Abrupt resonance changes in the impedance module, which occur in these characteristics under direct-current voltage (up to 10 V) applied to the composite nanostructure, are associated with the electron tunneling between numerous quantum wells arranged along the C axis of the layered matrix. Quantum-dimensional phenomena in these structures are manifested under a vertical transfer of carriers through nanoscale deformed (distorted) parts of the crystal layers, which are located between the ferroelectric inclusions. The transfer of carriers in the composite nanostructure takes place in the presence of a deformation gradient, which is created in the layered crystal along the C symmetry axis and causes manifestation of the flexoelectric effect in the GaSe matrix. Besides, we studied the influence of optical irradiation on the processes of the accumulation and vertical transfer of the carriers in the composite nanostructures (p-GaSe intercalated by KNO3). An essential increase of electrical capacity of the composite nanostructures under their illumination has been determined. | P1 11 |
| 17:00 | Investigation of crystalline qualities of silicon and tin doped beta-Ga2O3 film Authors : K. Takakura, S. Funasaki, M. Takahara, J. Kudou, I. Tsunoda, H. Ohyama, T. Nakashima, M. Shibuya, K. Murakami, E. Simoen, C. Claeys Affiliations : KNCT, KNCT, KNCT, KNCT, KNCT, KNCT, CDK, Echo mother, Japan gaschemi, imec, imec Resume : The development of devices composed of chemically abundant and ecological friendly materials is important. Gallium oxide (b-Ga2O3) is a wide band gap semiconductor, and is composed of chemically abundant materials. Application of b-Ga2O3 as transparent electrode or gas sensor seems feasible, because the electric conductivity of b-Ga2O3 increases by impurity doping. We have realized growth of undoped films by RF magnetron sputtering. However, the conductivity of the undoped film is very low. To increase the conductivity, impurity doping seems to be effective. In this work, silicon and tin is doped in the film.
The b-Ga2O3 films were grown on Si (001) by RF magnetron sputtering. The used target was 5N-sintered Ga2O3. The sputtering was performed in an argon/oxygen mixture gas ambient at RT at 2 Pa. To dope the impurities into the b-Ga2O3 film, the impurity was present on the target during the sputtering. After the deposition, the films were annealed at 600˚C for 15 min.
From the determination by EDX measurement, the doped impurities in the Ga2O3 films are a few atomic %. Also, growth of the Ga2O3 films on the substrates is confirmed by XRD measurements. At high impurity doping, undesirable phases such as e-Ga2O3, Sn2O3 and the others appeared. It is shown that the conductivity of the Si doped films were only two or three times increased. In contrast, the conductivity increased by three orders of magnitude for Sn doping. | P1 12 |
| 17:00 | Synthesis and electrical property study of highly conductive indium oxide nanowire arrays Authors : Soying Kwok, Xing Xie, Chundong Wang, Zhenzhen Lu, Wenjun Zhang Affiliations : Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Sciences, City University of Hong Kong, Hong Kong, China Resume : Recently, the study on one dimensional (1D) oxide nanowires have drawn great attention due to their great application potentials in various fields such as electronics, optics and photonics. Among them, indium oxide (In2O3) nanostructure-based transistors, memory devices and gas sensors have been demonstrated. In2O3 has a wide band gap about 3.6-3.8 eV, and the as-prepared In2O3 nanostructures present in general n-type conductivity mainly due to the existence of oxygen vacancies. To improve the performance of devices based on In2O3 nanostructures, control of their electronic and transport properties is essential. Various approaches have been reported thus far to tune the electrical properties of In2O3 nanostructures. However, the progress is still not so significant, e.g., doping with zinc led to the reduction of resistivity of In2O3 nanowires by only one order of magnitude from 1.8 x 10-1 to 2.2 x 10-2 Ω cm in the previous literatures.
In this work, we report the synthesis of highly conductive In2O3 nanowire arrays by chemical vapor deposition (CVD) method with NH3 introduced. The morphology, structure, and composition of the In2O3 nanowires were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS). By evaluating the field effect transistors (FET) constructed with single nanowire, the electronic and transport properties of the nanowires were characterized. It was revealed that the resistivity of the In2O3 nanowires was reduced to 9.9 x 10¬-3 Ω cm, even smaller than that of Zn-doped In2O3 nanowires. The field effect mobility and carrier concentration of the In2O3 nanowires were further estimated to be 270 cm2V-1s-1 and 2.32 x 1018cm-3 respectively. The possible mechanism for the reduction of resistivity of non-doped In2O3 nanowires arrays prepared by our approach was also discussed. The highly conductive In2O3 nanowires in an array structure may benefit their applications in solar cells and transparent transistors. | P1 13 |
| 17:00 | Fabrication of Greigite and Pyrite Iron Sulfide Nanocrystals Authors : M. Liu, C. Yan, J. Bell Affiliations : School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology Resume : Iron sulphides are recognized as advanced inorganic materials due to their unique magnetic and electrical properties and promising applications, such as high-energy density batteries, diagnostic materials, infrared sensors and photo catalysts [1-6]. In nature, there are several types of iron sulphides with different ratio of Fe:S. The magnetic and electric properties are strongly related to the stoichiometric ratio between Fe and S as well as crystal structure. Among these iron sulphides, greigite and pyrite attract much attention. Greigite is a sulphide counterpart of the well-known iron oxide spinel magnetite mineral with formula Fe3S4. Submicrometer Fe3S4 nanoparticles occur in nature as magnetosomes in magnetotactic bacteria and as inclusions in geological sediments. These magnetic greigite Fe3S4 nanoparticles have been recently developed for cancer therapy by magnetic hyperthermia [1,2]. Pyrite nanocrystals with formula FeS2 is a very attractive next-generation photovoltaic material since it is abundant in nature and nontoxic [3-6]. Moreover, some studies proved that pyrite exhibits a very high absorption coefficient, which is two orders of magnitude higher than that of crystalline silicon, but has comparable band gap energy [3].
Up to now, many synthesis methods have been developed to prepare these two very important materials, such as sol-gel, hydrothermal method, precursor thermal decomposition method and solid reaction method [1-6]. Size-control and even shape-control on these two materials have been already achieved. However, controllable synthesis of these two important materials from a simple reaction system has not been reported yet. Herein, we report a simple oleylamine system can develop pure greigite Fe3S4 and pyrite FeS2 by adjusting reaction temperature.
References:
[1] J.H.L. Beal, S. Prabakar, N. Gaston, G.B. The, G. Williams, R.D. Tilley, Chem. Mater. 2011, 23, 2514.
[2] Y. Chang, S. Savitha,, S. Sadhasivam, C. Hsu, F. Lin, J. Colloid Interface Sci. 2011, 363, 314.
[3] Y.Bi, Y. Yuan, C.L. Exstrom, S.A. Darveau, J. Huang, Nano Lett. 2011, 11, 4953.
[4] W. Li, M. Doblinger, A. Vaneski, A.L. Rogach, F. Jackel, J. Feldmann, J. Mater. Chem. 2011, 21, 17946.
[5] Z.J. Luan, L.Y. Huang, F. Wang, L. Meng, Appl. Surf. Sci. 2011, 258, 1505.
[6] M. Li, Q. Yao, G. Zhou, X. Qu, C. Mu, S. Fu, Cryst. Eng. Comm. 2011, 13, 5936. | P1 14 |
| 17:00 | Properties of sputtered NiO and NiAlO thin films Authors : G. Michael, V. Kampylafka, K. Tsagaraki, V. Binas, E. Aperathitis and G. Kiriakidis Affiliations : G. Michael, Physics Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece; V. Kampylafka, K. Tsagaraki, V. Binas, E. Aperathitis, Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology –FORTH-Hellas, P.O. Box 1385, Heraklion 70013, Crete, Greece; G. Kiriakidis, Physics Department, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece and Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology –FORTH-Hellas, P.O. Box 1385, Heraklion 70013, Crete, Greece Resume : Nickel oxide (NiO) is a p-type semiconductor, with direct band gap energy 3.6-4 eV, used in electrochromic, photovoltaic and sensor devices. Stoichiometric NiO is an insulator and Li, Al and Cu have been reported recently as possible impurity dopants in NiO which might enhance its properties.
In this work NiO and NiAlO thin films were fabricated by sputtering from Ni and Ni-Al targets, respectively, in Ar-O2 plasma, at 300W rf power and 5 mTorr pressure.
The films were examined for their structural, optical and electrical properties. Films deposited using the Ni target were polycrystalline single phase NiO films. The highest transmittance (25%) was observed for films deposited in 2.8% O2 in plasma, with band gap 3.64eV, they had p-type conductivity and resistivity 10 Ωcm..
Films deposited using the Ni-Al target in 2.8% O2 plasma, showed one XRD peak of the NiAl2O4 phase and a second small one of Ni or AlNi. EDX revealed also the existence of Al in the structure, 4 at.%. When compared to NiO films, the NiAlO films had higher transmittance 55%, optical band gap 3.76eV and resistivity 35 Ωcm.
Annealing up to 600oC improved the transparency of the films. The NiAlO films showed transmittance of 75% at 600oC whereas the NiO films had 75% transmittance at the annealing temperature of 500oC. Electrical measurements of NiO and NiAlO films are in progress, after which conclusions can be drawn on their potential applications in electrochromic and photovoltaic devices. | P1 15 |
| 17:00 | Adjusting the electronic and optical properties of mesoporous MCM-41 materials by Ti doping Authors : Maofeng Dou1,2 Tianhuang Yu2, Shengming Jin2, Clas Persson1,3 Affiliations : 1.Department of Material Science and Engineering, Royal Institute of Technology (KTH). 10044 Stockholm, Sweden 2. Department of Inorganic Materials, School of Resource Processing and Bioengineering, Central South University, 410083 Changsha, China 3. Department of Physics, University of Oslo, PO Box 1048 Blindern, 0316 Oslo, Norway Resume : Solid mesoporous materials with ordered pore structure have potential applications for catalysis, genome sequence, and chemical sensor, etc [1]. The common approach for synthesizing Ti doped mesoporous material MCM-41 (Ti-MCM-41) is using costly ethyl silicate and tetrabutyl titanate as inorganic sources. In this work, however, low cost water glass and TiCl4 was used as inorganic sources to synthesize Ti-MCM-41. Pore structures with different Ti doping concentrations were studied using small angle X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM) and N2 adsorption-desorption. It shows that Ti-MCM-41 has ordered mesopore structure with the preferable pore size of 2.60 nm and the specific surface area of 1030 m2/g. The pore framework structure was investigated via the Fourier transform infrared (FTIR) spectroscopy and the diffuse reflectance ultraviolet-visible (UV-vis) spectroscopy. We find that Ti is coordinated to four siloxy groups in low doping content. These results are compared with first-principles defect calculations within the density functional theory, employing the Perdew-Burke-Ernzerhof (PBE) functional as well as the Heyd-Scueria-Ernzerhof (HSE) hybrid functional [2]. Here, we find overall good qualitative agreement with the experimental characterization, and that the HSE potential improves, compared with PBE approach, the electronic structure and optical absorption of the theoretical modeling.
References:
1. B. M. Venkatesan and R. Bashir, Nature Nanotech. 615, 6 (2011).
2. G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993). | P1 16 |
| 17:00 | Single-step synthesis and characterization of nanocrystalline BaAl2O4 Authors : Robert Ianos, Radu Lazau, Roxana Babuta, Silvana Borcanescu, Cristian Boruntea Affiliations : Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, P-ta Victoriei no. 2, Timisoara, 300006, Romania Resume : Various barium aluminate, BaAl2O4, powders have been prepared by combustion synthesis. Barium nitrate, barium nitrite and aluminum nitrate were used as oxidizing agents. Urea, acrylamide and different amino-acids (glycine, alanine) were used as reducing agents (fuels). Single fuel and fuel mixture recipes have been tested. TG-DTA analysis was used to monitor the heating behavior of the precursor solutions. The resulted powders were characterized by XRD, SEM, BET. Properties of the combustion synthesized powders (phase composition, crystallite size, specific surface area, morphology) were discussed and related to the synthesis conditions. Experimental results evidenced that fuel mixtures considerably enhanced the formation of pure nanocrystalline BaAl2O4, due to the higher exothermicity of the redox process. | P1 17 |
| 17:00 | Anodic aluminum oxide: to the limits and beyond Authors : Stefan Ostendorp (a), Jörn Leuthold (a), Yong Lei (a,b), Gerhard Wilde (a) Affiliations : a) Institute of Materials Physics and Center for Nanotechnology CeNTech, WWU Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany; b) Institut für Physik & IMN (ZIK) MacroNano, Technische Universität Ilmenau, D-98684 Ilmenau, Germany Resume : Anodic aluminum oxide (AAO) as a template or deposition mask is a promising alternative to lithography techniques in terms of creating tailorable surface nanostructures on large scales with low fabrication costs. The easy way to change structural parameters like size shape and spacing of the formed nano-structures is the outstanding characteristic of this technique. For fundamental physical studies or many potential applications in sensing, optics or electronics 0- and 1-dimensional nano-structures supposed to be highly regular arranged. Here the nano-structuring technique based on AAO shows certain limitations. There are only a few narrow parameter ranges reported allowing to form hexagonally regular porous AAO. Therefore the structural parameter range of regular surface nano-structures prepared by AAO is limited. Here we present our recent progress in understanding and extending these limitations by detailed studies of AAO formation in oxalic acid solutions under varying anodization conditions. Therefore we use an improved anodization setup with an enhanced control of the process temperature. By quantitative regularity measurements we are able to tune the anodization conditions to obtain regular AAO with structural parameters not reported before. Furthermore we demonstrate a novel fabrication technique which allows essential low AAO growth rates at elevated anodization voltages to realize through-hole structures suitable for surface nano-structuring purposes. | P1 18 |
| 17:00 | Polymer nanosphere array-assisted electroless deposition of ZnO rods Authors : N. Preda*, M. Enculescu, M. Socol, I. Zgura, I. Enculescu Affiliations : National Institute of Materials Physics, Bucharest-Magurele, P.O. Box MG-7, R-77125, Romania Resume : The electroless technique is a simple, efficient and suitable method for industrial preparation. In the present study ZnO nanostructures were obtained by electroless deposition using polymer nanosphere arrays. The polymer latex spheres were assembled on glass substrates using dip-coating technique. The next step was to employ the polymer arrays in the growth of nano-sized ZnO particles by electroless method. The ZnO nanostructures were characterized by X-ray diffraction (XRD), photoluminescence (PL), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle (CA) measurements. The XRD studies demonstrate that the ZnO nanoparticles have a hexagonal wurtzite structure. In the PL spectra of ZnO films deposited on polymer array an ultraviolet emission band peaked at about 2.9 eV is observed. The SEM images prove that aligned rod-shape ZnO particles with a fairly uniform diameter of around 500 nm and length of 1 μm are synthesized. From the CA measurements it was found that the electroless deposition on polymer sphere arrays of ZnO leads to an improvement of its hydrophobic properties. Such ZnO nanostructured films can have potential applications in areas which properties such UV protection, self-cleaning or superhydrophobicity are required.
Acknowledgements: This work was supported by National Fellowship UNESCO-L’OREAL “For Women in Science” and by the CNCSIS-UEFISCSU, Project number PNII-RU code 59/2010 (Contract no. 18/28.07.2010). | P1 19 |
| 17:00 | Ion beam study of InAs quantum dots embedded in Si Authors : D. Pelloux-Gervais (a), D. Jalabert (b), B. Canut (a), A. El Akra (a,c), M. Gendry (c), H. Dumont (c), C. Bru-Chevallier (a) Affiliations : (a) Université de Lyon, Institut des Nanotechnologies de Lyon INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne, F-69621, France ; (b) CEA-INAC/UJF-Grenoble1 UMR-E, SP2M, LEMMA, Minatec Grenoble, F-38054 ; (c) Université de Lyon, Institut des Nanotechnologies de Lyon INL-UMR5270, CNRS, Ecole Centrale de Lyon, Ecully, F-69621, France Resume : The insertion of quantum objects made of a small band gap semiconductor material inside a larger band gap material has been extensively investigated. One reason for such interest arises from the original physical properties (especially the optical ones) which can be observed in such systems due to the size dependent quantum confinement effect. This work is part of a program which aims the realization of light emitting devices based on InAs quantum dots (QDs) inserted in a silicon matrix. Our contribution to this project is to perform ion beam analysis (IBA) of the Si/InAs QDs/Si system using Rutherford Backscattering Spectrometry in Channeling geometry (RBS-C) and Medium Energy Ion Scattering (MEIS). The first technique enables the determination of QD atomic composition and element areal density while the second one leads to defect and strain profiles with subnanometer depth resolution. We present here IBA results obtained from InAs QDs deposited on Si by molecular beam epitaxy. The presence of excess As atoms in the Si cap layer is highlighted thanks to RBS data. Starting from this statement we can discern two contributions to the As channelling profile from MEIS experiment: one from QD As atoms and another one from excess As atoms. QD strain state and crystal orientation with respect to the Si substrate are also discussed in the light of MEIS crystallographic pole figures. | P1 20 |
| 17:00 | Synthesis of ZnO nanocrystals and Ag/ZnO heterostructures by colloidal method Authors : Arunkumar Panneerselvam, Mark Green, Hiren R. Kotadia, Omid Mokhtari, Samjid H. Mannan, Michael P. Clode Affiliations : Department of Physics and Department of Engineering, King's College London, The Strand, London WC2R 2LS, U.K. Resume : Zinc oxide is a material exciting great interest due to its semiconducting and piezoelectric properties. These properties have led to numerous applications in fields such as electronics, cosmetics, photovoltaics, photocatalysis, bio and gas sensors amongst others (1). Thermal decomposition of precursors in a coordinating solvent is one of the most versatile approaches for the synthesis of size, shape-controlled crystalline nanoparticles with readily exchangeable surface properties (2).
In this work, we have synthesised ZnO nanocrystals and Ag/ZnO heterostructures using zinc carboxylates in the presence of hexadecylamine or polyethyleneglycoldibutylether. The results of the as-obtained products characterised by X-ray diffraction, transmission electron microscopy and photoluminescence studies will be presented.
References:
1. A. Wei, L. Pan and W. Huang, Mat. Sci. Eng. B, 2011, 176, 1409.
2. M. Green, J. Mat. Chem., 2010, 20, 5797. | P1 21 |
| 17:00 | Titanium dioxide nanoparticles supported by ultra-porous alumina: Phase transition at different temperature and photo catalytic properties influence Authors : M. Bouslama1,2, M. C. Amamra1, Z. Jia 1 , M. Ben Amar 1, K. Chhor 1, M. Abderrabba 2, J.-L. Vignes 1, A. Kanaev 1 Affiliations : 1 Laboratoire des Sciences des Procédés et des Matériaux C.N.R.S., Institut Galilée, Université Paris 13, 93430 Villetaneuse, France 2 Unité de recherches de Physico-chimie Moléculaire, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université du 7 Novembre, Carthage, Tunisie Resume : The size-selected TiO2 nanoparticles (NP) impregnation into monolithic ultraporous alumina (UPA) permits new nanoparticulate photocatalysts with an extended activity into the high-temperature range up to 1000 °C. This is explained by anatase phase stability due to the inhibited NPs aggregation. In this communication we report on the effect of the NP polymorphism and size on the photo catalytic ethylene gas decomposition. Use of UPA supports of gamma, theta and alpha polymorphs, covered with silica or not, and thermal treatment at different temperatures allow modification of the NP’s size and crystalline composition. In all cases, the electronic coupling between titania and UPA support is found to affect nanoparticle polymorph. Especially in case of a separated layer of silica witch increases the TiO2 anatase stability. The main conclusion is that anatase NPs exhibit the higher activity compared to rutile and composite anatase/rutile NPs. The rutile activity strongly decreases with size, while that of anatase NPs does not appreciably change for 5 nm ≤ 2R ≤ 10 nm. The activity of the last strongly decreases when rutile phase is nucleated onto anatase. | P1 22 |
| 17:00 | Synthesis of highly oriented (111) crystalline NiO nanopillar by oblique angle deposition at room temperature Authors : S.Nandy, L.Pereira, G.Gonçalves J.V.Pinto, P.Barquinha, E.Elangovan, R.Martins and E.Fortunato Affiliations : CENIMAT/I3N, Departmento de Ciencia dos Materials, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa and CEMOP-UNINOVA, 2829-516 Caparica, Portugal Resume : Thin film based on semiconductor belongs to transparent conducting oxide (TCO) materials which exhibit exceptional optoelectronic properties, have tremendous opportunity in modern transparent electronics era. Moreover in photovoltaic application TCO thin film with textured surface or nanostructure morphology can enhanced the solar cell performance as increasing of light scattering and absorption due to morphology. Therefore the modified thin film technology e.g. oblique angle deposition (OAD) can serve our purpose to synthesized well aliened nanostructure thin film which material we want to deposit. This OAD is kind of self-shadowing of impinged atoms by neighbouring atoms through continuous adjusting the polar and azimuthal angles between the substrate surface normal and the incident deposition flux. The growth of the nanostructure operates under the conditions like limited surface diffusion and controlled motion of the atoms.
This is the first report on synthesis of highly oriented (111) crystalline Nickel Oxide (NiO) nanopiller as thin film form on silicon and glass substrates by RF magnetron sputtering using OAD method at room temperature. Cross-sectional FESEM picture shows that how the inclined nanopiller formed due to deposition of NiO with oblique angle. The shift of the diffraction peak (Δθ=0.55°) confirmed the lattice deformation (~Δa=0.07Å) of NiO unit cell which is due to tensile strain produced within the film during growth. This may because of the preferential growth of elongated unit cells of NiO along the c-axis due to controlled surface diffusion and mobility of atoms on the substrate plane during OAD. A positive shift of XRD peak for post annealed films have been observed, indicating the released of stress due to thermal energy. The change of nanopiller orientation also observed for that. | P1 23 |
| 17:00 | Structural, Electrical, and Optical Properties of Atomic Layer Deposition Hf-doped ZnO Films Authors : Yang Geng, Li-Heng Xie, Qing-Qing Sun, Peng Zhou, Shi-Jin Ding, Hong-Liang Lu *, and David Wei Zhang Affiliations : State Key Laboratory of ASIC and System, Department of Microelectronics, Fudan University, Shanghai 200433, China Resume : High quality Hf-doped ZnO (HZO) films were grown on Si, thermally grown SiO2, and glass by atomic layer deposition (ALD) at 220 oC using a BENEQ-TFS 200 system with various Hf doping. Diethyl-zinc (DEZn) and Tetrakis(ethylmethylamino)hafnium (TEMAH) were the metal precursors for Zn and Hf, respectively. The Hf-doping is then achieved by growing ZnO and HfO2 alternatively; m (m=40,20,10,7,5) cycles of ZnO are grown plus one cycle of HfO2 to achieve the particular at.% Hf doping, and then this sequence is repeated n (n=12,25,50,70,100) times to obtain the desired thickness (~100nm). The thickness and optical properties of the HZO films were determined by spectroscopic ellipsometry. It demonstrated that the thickness is in the range from 96.5 to 103.2nm and the growth rate is about 0.2 nm per cycle for ZnO and 0.1 nm per cycle for HfO2, respectively. Optical characterization was also performed using the transmittance spectra and room-temperature photoluminescence. X-ray diffraction was used to examine the crystal structure of the HZO films. The surface roughness of the HZO films was characterized using atomic force microscopy. Hall measurements were carried out to obtain the electrical properties. The results showed that the resistivity for the prepared films first decreases and then increases with the Hf doping increasing. The film with the m value of 10 has the lowest resistivity. | P1 24 |
| 17:00 | Evolution of the magnetoresistance properties of ion beam synthesized Fe nanoparticles in SiO2 upon electron-beam annealing Authors : J. Leveneur(a,b), J. Kennedy(a), G. V. M Williams(c), J. B. Metson(b), and A. Markwitz(a) Affiliations : a) National Isotope Centre, GNS Science, 30 Gracefield Road, Lower Hutt, New Zealand; (b) Department of Chemistry, The University of Auckland, Private Bag 92019 , Auckland, New Zealand; (c) The MacDiarmid Institute for Advanced Materials and Nanotechnology, SPCS, Victoria University, PO Box 600, Wellington, New Zealand Resume : The race for smaller, faster and more efficient microelectronic systems has opened the door for incredible developments in nanotechnology and nanomaterials. It has been found that decreasing the dimensions of a material to the nanometre level has dramatic effects on the material properties. Magnetic nanoclusters, clusters of magnetic atoms under 100 nm in diameter, display a range of unique properties, such as superparamagnetism [1], and are thus of interest in spintronics [2], computer data storage [3], and even medicine [4]. There is a growing interest in finding new controllable ways to synthesise nanoclusters and understand their properties.
In this study metallic, Fe nanoclusters were grown at the surface of a SiO2 film on Si using low-energy ion implantation and electron beam annealing. Ion implantation leads to the formation of Fe nuclei which coalesce and protrude from the surface under electron beam annealing. This material was observed to display large positive magnetoresistance with linear behavior above 2 T at 300 K.[5] We report the effect of annealing-induced structural and composition changes observed with ion beam analysis, microsopy and X-ray spectroscopy techniques on the magnetoresistance properties.
[1] Fonseca FC et al. (2002) Phys Rev B 66:104406
[2] Betzig E et al. (1992) Appl Phys Lett 61:142
[3] Sun S et al. (2000) Science 287:1989
[4] L? A S et al. (2001) J Surg Res 95:200-206, 2001
[5] J. Leveneur, et al. (2011) Appl Phys Lett 98:053111 | P1 25 |
| 17:00 | Investigations of the structural, optical and electrical properties of Nd-doped ZnO thin films deposited by spray pyrolysis Authors : I. Chaki1, N. Hassanain1 and M. Abd-Lefdil1 R. Diaz2 and P. Pierito2 A. Slaoui3 K. Nouneh4 G. Schmerber5, S. Colis5 and A. Dinia5 K. Nouneh4 G. Schmerber5, S. Colis5 and A. Dinia5 Affiliations : 1-Université Mohammed V-Agdal, Laboratoire de Physique des Matériaux, Faculté des Sciences, B.P. 1014, Rabat, Morocco 2-Departamento de Física Aplicada C-XII, Universidad Autónoma de Madrid, Spain. 3-InESS, UMR CNRS 7163, UDS, 23 rue du Loess, B.P. 43, F-67037 Strasbourg Cedex 2, France 4-Institute of Nanomaterials and Nanotechnology, Moroccan Foundation for Advanced Science, Innovation and Research MASciR, Rabat, Morocco. 5-IPCMS, UMR CNRS 7504, UDS-ECPM, 23 rue du Loess, B.P. 43, F-67034 Strasbourg Cedex 2, France Resume : Nd-doped ZnO thin films are deposited on glass substrate by spray pyrolysis at 350°C. X ray diffraction (XRD) analyzes show that the films are polycrystalline and present the expected wurtzite structure. Nd doping has no sensitive effects on the structure and does not lead to any secondary phase. Atomic force microscopy (AFM) shows that the surface is rough with roughness around 20 nm. All films exhibit a high transmittance around 80% in the visible range with a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge at 3.3 eV. Photoluminescence measurements show no emission from Nd3+ up to 1000 nm. Appropriate annealing will be performed to study the possible energy transfer between ZnO matrix and Nd3+ ions. Hall effect measurements showed low resistivities and interesting carrier mobilities which makes these films promising for photovoltaïc devices. | P1 26 |
| 17:00 | Microwave-assisted synthesis of mesoporous MIL-100(Al, Cr, Fe) nanoparticles for thin film elaboration Authors : A. Garcia Márquez 1,2; A. Demessence 1,2 ; A. Platero1; D. Heurtaux 1; P. Horcajada 1; C. Serre 1; C. Boissière 2; D. Grosso 2 and C. Sanchez 2. Affiliations : 1. ILV, Université de Versailles, CNRS UMR 8180, France 2. LCMCP, Collège de France. Paris, France. Resume : Metal-Organic Frameworks (MOFs) are crystalline porous materials with outstanding properties. Their high specific surface and their microporous structure makes them promising candidates for applications in separation, magnetism, catalysis, greenhouse gas storage, drug carriers and contrast agents for imaging.[1]
In order to optimally exploit such properties, the processing of such materials via coating or casting techniques plays a key role in the preparation of solid substrate-supported nanostructured MOFs with applications in optics, microelectronics or sensing.[2]
Currently, the optimisation of the synthesis of MOFs at the submicron sizes is intensively studied.[3] The microwave-assisted method has been revealed as an interesting route for the rapid preparation of homogeneous and monodisperse nanoscale MOF with important yields.
We report here the microwave-assisted synthesis of nanoparticles of the highly mesoporous and stable metal(MIII=Al,Fe,Cr) trimesates MIL-100. Moreover, optical quality thin films were produce by dip-coating using these particles dispersion, characterizing their layer porosity via ellipsometric porosimetry under different vapors.
[1] Acc. Chem. Res.2005, 38, 215; Chem. Soc. Rev., 2009, 1201; Chem. Soc. Rev., 2011, 40, 550; Chem. Rev., 2012, dx.doi.org/10.1021/cr200256v
[2] Chem. Soc. Rev. 2011, 40, 1081
[3] J. Mater. Chem., 2010, 21, 2220. | P1 27 |
| 17:00 | Effect of substrate temperature on the electrical and optical properties of pulsed laser deposited ZnO thin films Authors : S. Nagar and S. Chakrabarti Affiliations : Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India Resume : Zinc oxide films of thickness around 300nm have been deposited over <001> sapphire substrates by pulsed laser deposition technique at temperatures varying from 400°C to 800°C. The effect of different deposition temperatures on the electrical and optical behavior of the thin films has been investigated. Room temperature Van der Pauw Hall measurement depict that the carrier concentration decrease from 4.23 ?1018 cm-3 at 450°C to 1.45 ?1018 cm-3 at 650°C, after which it starts to increase to reach a value of 3.16 x 1018 cm-3 at 800°C. The corresponding Hall mobility values are 8.69 cm2/Vsec, 25.6 cm2/Vsec and 15.7 cm2/Vsec respectively. However, not much variation is observed in the concentration and mobility values when the Hall measurement is carried out at temperatures varying from 80-300K. Temperature-dependent photoluminescence studies performed on the films reveal a strong near band edge (NBE) emission around 3.36eV at 8K, corresponding to the donor-bound exciton (D°X) peak. The D°X peak dominates at lower temperature but at higher temperatures, the free-exciton peak starts to dominate in all the samples. The enhanced thermal dissociation of bound excitons into free excitons with temperature results in such an observation. Moreover, the deep-level emission shows a yellow shift up to a temperature of 650°C after which it shows a shift towards the green emission which is attributed to oxygen vacancies and zinc interstitials. DST, India is acknowledged. | P1 28 |
| 17:00 | Films of tunable ZnO hybrid nanostructures prepared by a surfactant-mediated soft synthesis route Authors : Benoit P. Pichon,1 Didier Tichit,2 Corine Gérardin2 Affiliations : 1 Institut de Physique et de Chimie des Matériaux de Strasbourg 2 Institut Charles Gerhardt Montpellier Resume : Films of ZnO hybrid nanostructures are very attractive because of their high potential in applications like photocatalysis or photovoltaics. Indeed ZnO is a wide band gap (3.37 eV) semiconductor having a high electron – hole binding energy (60 meV), which has excellent electronic and optical properties. Films of ZnO hybrid nanostructures were prepared by a soft chemical synthesis route from ZnO crystal seeds in aqueous medium, in the presence of alkylsulfates of different chain length acting as structure-directing agents. While films of arrayed single crystal ZnO nanorods were formed with short alkylsulfates, from C6 to C8 alkylene chains, hybrid lamellar ZnO with a plate-like morphology were obtained with C10 to C18 alkylsulfates. In the case of the short alkylsulfates, due to the interaction between the sulfate groups and the Zn2+ planes of the ZnO structure, the growth along the c axis is partially inhibited and smaller aspect ratios of the nanorods are obtained than in alkylsulfate-free conditions. In the case of the hybrid lamellar ZnO structures which consist in ZnO layers intercalated with alkylsulfate bilayers, the structural characteristics depend on the alkylene chain length. Basal spacings increase linearly with the chain length, while the plate size decreases dramatically when the chain length exceeds C14. Finally, the combination of ZnO and organic substructures was demonstrated to be a well suited pathway to tune the optical properties of these hybrid materials. | P1 29 |
| 17:00 | Raman study of Mn-doped ZnO thin films Authors : M. F. Cerqueira, A.G. Rolo, T. Viseu, J. Ayres de Campos, T. de Lacerda-Ar? F. Oliveira, M. Vasilevskiy, E. Alves* Affiliations : University of Minho, Centre of Physics and Physics Department, 4710 – 057 Braga, Portugal * ITN, Ion Beam Laboratory, Unit of Physics and Accelerators, E.N. 10, 2686-953 Sacav? Portugal Resume : Recently, dilute magnetic semiconductors (DMS) have attracted much attention for their promising functionalities in spintronics. Since ZnO is a particularly interesting type of transparent conducting oxide [1], much attention has been dedicated to ZnO-based DMSs. Although theoretical calculations predicted ferromagnetism at room temperature [2], magnetization measurements have only found low magnetic ordering temperatures or no ferromagnetism at all for some ZnO-based semiconductors [3]. We believe that the magnetic properties in these diluted systems may be sensitive to the sample preparation method.
In this work we report the successful preparation of transparent ZnO thin films grown by rf sputtering and doped with Mn by implantation and by co-sputtering. Raman study of undoped and Mn-doped ZnO thin films are presented and discussed, focusing on the Raman band on the LO phonon spectral region (500-600 cm−1), as a function of doping method and dose. We expect to contribute to the clarification of the assignment of some additional phonon modes to this doping element, and to the understanding of the properties of the dopant that may be relevant to improve the material and device quality.
[1] Zhang Xiaodan, Fan Hongbing, Zhao Ying, Sun Jian, Wei Changchun, Zhang Cunshan, Appl. Surface Science 253, 3825 (2007)
[2] T. Dietl, H. Ohno, F. Matsukura, Phys. Rev. B 63, 195 (2001)
[3] M. Bouloudenine, N. Viart, S. Colis, J. Kortus, and A. Dinia, Appl. Phys. Lett 87, 052501 (2005) | P1 30 |
| 17:00 | Novel nanostructured photocatalyst consisted of TiO2 nanoparticles immobilized in ultraporous monolithic alumina Authors : M. Bouslama 1,2, M. C. Amamra 1, K. Chhor 1, M. Abderrabba 2, J.-L. Vignes 1, A. Kanaev 1 Affiliations : 1 Laboratoire des Sciences des Procédés et des Matériaux C.N.R.S., Institut Galilée, Université Paris 13, 93430 Villetaneuse, France 2 Unité de recherches de Physico-chimie Moléculaire, Institut Préparatoire aux Etudes Scientifiques et Techniques, Université du 7 Novembre, Carthage, Tunisie Resume : The extremely low density and high porosity of monolithic alumina makes them interesting for applications as supporting matrixes for nanomaterials. In this communication we present a novel nanostructured photocatalyst consisted of non-aggregated TiO2 nanoparticles immobilized in ultraporous monolithic alumina with an enhanced efficiency.
We have prepared the new photocatalyst by several impregnations-drying cycles of size-selected TiO2 nanoparticles into monolithic ultraporous alumina of gamma, thetaand alpha polymorphs, treated or not with silica precursor, and thermally above 350°C to form most active anatase TiO2 polymorph. An evanescently low absorption of the UPA matrixes was validated by spectral measurements: the only material absorbing UVA photons were titania nanoparticles.
The photocatalytic activity of these catalysts prepared in different conditions has been studied at UVA illumination. The best results are obtained in the matrixes of gamma and theta polymorphs of large specific area, which surface is covered by thin silica layer. These materials prohibit aggregation of the anatase nanoparticles at mass loading as high as 30wt% after thermal treatment with a temperature up to 1000°C. These photocatalytic media show considerably higher efficiency compared to the reference P25 Degussa sample. This activity is conserved over the large temperature range, while it decreases as soon as the nanoparticle aggregation takes place and the rutile phase appears. | P1 31 |
| 17:00 | The growth and micro-Raman characterization of GaN nanorods Authors : P. Kamyczek1, Z. R. Zytkiewicz2, E. Placzek-Popko1, E. Zielony1, M. Sobanska2, A. Reszka2, K. Klosek2 Affiliations : 1 Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland; 2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland Resume : Micro-Raman spectroscopy was used to study strain in GaN nanorods grown by plasma-assisted molecular beam epitaxy on Si(111) substrates. The growth comprised of a substrate deoxidation, exposure to a nitrogen flux and self-organized growth of nanorods under nitrogen-rich conditions, without catalyst. The morphology of the samples was characterized by high resolution scanning electron microscopy. The GaN nanorods were ~350 nm long with diameter of ~25nm, homogenously distributed, oriented along c-axis, perpendicularly to the substrate. Two types of nanorods grown at Ga source temperature TGa ~820°C and 800°C were studied. The nanorods in the sample A exhibit partial coalescence whereas in the sample B an ensemble of separated nanorods was formed. Micro-Raman spectroscopy was carried out with the use of Jobin–Yvon’s T64000 system equipped with a CCD camera. 514.5 nm line of Ar2+ laser was used as an excitation source. Raman spectra show Si related signal at ~521cm-1 and E2high GaN mode at 568cm-1. The intensity of the mode is, as expected, higher for the sample A. Comparison of the Raman signals with bulk Si and GaN let us conclude that substrate and nanorods are strain free. A slight red-shift of the E2high mode for higher laser powers (568 cm-1 at 4mW down to 567.4 cm-1 at 90mW) is associated with local increase of temperature upon laser illumination. The temperature of the samples was estimated using Stokes’ / anti-Stokes’ intensity ratio of the Si related signal. | P1 32 |
| 17:00 | Impedance spectroscopy of ZnTe-Ti/Al Schottky contacts with CdTe quantum dot Authors : E. Zielony1, E. Płaczek-Popko1, J. Trzmiel1, G. Karczewski2 Affiliations : 1 Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland; 2 Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw, Poland Resume : Recently, self organized quantum dots (QDs) were investigated widely for several years because of their potential application in QD semiconducting devices, such as lasers, detectors of radiation or solar cells. Quantum dot layers embedded in a semiconducting structure behave like giant traps and thus the techniques used to study deep traps become applicable for the structures.
Complex impedance spectroscopy has been applied to investigate the dielectric response of ZnTe-metal Schottky contacts. The measurements have been performed in the frequency range from 0.2Hz to 3MHz and at temperature range from 77K to 300K. The objects of the investigations were the CdTe quantum-dot structures embedded in ZnTe matrix and a reference sample without quantum dots. Combined modulus and impedance spectroscopic plots were analyzed to study the response of the structures. For both samples the data were fitted with the simple RC circuit composed of a depletion layer capacitance in parallel with contact resistance and a resistance of a bulk ZnTe material in series. The activation energy of the trap observed for the reference sample obtained from the Arrhenius plot of the resistance, impedance and modulus equals to 0.4eV. For the quantum-dot sample the value of activation energy determined with the help of the same methods are equal to 0.2eV. In conclusion it has been assumed that the 0.4eV trap is related to ZnTe host material whereas the 0.2eV trap has been attributed to QDs. | P1 33 |
| 17:00 | Patterning growth of ONWs on ITO and TiO2 surfaces Authors : Y. Oulad-Zian, J. R. Sanchez-Valencia, A. Borras, A. R. Gonzalez-Elipe and J. P. Espinos Affiliations : Instituto de Ciencia de Materiales de Sevilla (ICMS, CSIC-US), Nanotechnology on Surfaces Lab., C/ Américo Vespucio 49, 41092, Sevilla, Spain. Resume : In this communication we show the basis for the patterning formation of organic nanowires (ONWs) by vacuum methods. In previous references1 we have report on the vacuum fabrication of ONWs based on π conjugated molecules on different substrates. Thus, supported single crystal ONWs of metal porphyrins (PdOEP, PtOEP), metal phthalocyanines (CuPc, CoPc, FePc) and perylenes (MePTCDI) grow at low temperature on metal and oxide substrates of tailored surface roughness. Herein we focus on the patterning formation of PdOEP NWs on porous TiO2 thin films. Thus we present the effect on the pretreatment of this wide band gap semiconductor on the controlled formation either of hybrid thin films (PdOEP filling the porous structure of the TiO2 film) or high density arrays of ONWs supported on the film surface. Hybrid materials and ONWs were characterized by SEM, UV-Vis absorbance and fluorescence. Moreover, in situ XPS experiments were carried out in order to fully describe the mobility of the organic molecules on the porous structure.
[1] A. Borras, M. Aguirre, O. Groening, C. Lopez-Cartes, P. Groening, Chem. Mater. 2008, 20, 7371. | P1 34 |
| 17:00 | Co-doping and (Co,Mo) co-doping effect on the structural, optical and electrical properties of TiO2 thin films grown by PLD Authors : S. Rout1*, S. Dalui1,2, A.J. Silvestre2, A. Amaral3 and O. Conde1 Affiliations : 1Universidade de Lisboa, Faculdade de Ciências, Departamento de Física and ICEMS, 1749-016 Lisboa, Portugal; 2Instituto Superior de Engenharia de Lisboa, Área Departamental de Física and ICEMS, 1959-007 Lisboa, Portugal; 3Instituto Superior Técnico, Departamento de Física and ICEMS, 1049-001 Lisboa, Portugal Resume : Transition metal doped TiO2 films have attracted much attention due to their potential application in new generation spintronics and optoelectronics devices. The effect of Co-doping and (Co,Mo) co-doping on the structural, optical and electrical properties of TiO2 film has been investigated. Co-doped and (Co,Mo)-doped TiO2 films (with 5 at%Co, 1 and 3 at%Mo) were deposited by pulsed laser deposition (PLD) onto Al2O3(0001) and STO(001) substrates. The films grown on Al2O3 were deposited at Ar pressure of 8×10-4 mbar and at a substrate temperature of 350 oC while films on STO were deposited at O2 pressure of 4.5×10-5 mbar and a substrate temperature of 500 oC. The X-ray diffraction analyses reveal that all films deposited on Al2O3(0001) are anatase single phase with (112) orientation, whereas films on STO are anatase (004) oriented. Depending on the dopant type and substrate used different surface morphologies were observed. All the films grown on sapphire show a semiconductor behavior while films grown on STO can present a metallic like-behavior, depending on the dopant type. Optical measurements for films deposited on Al2O3 show band gap values red shifted (n-type doping) when compared to undoped films. The nature of the carriers was confirmed by Hall measurements.
Acknowledgement: This work was financially supported by Fundação para a Ciência e Tecnologia (FCT), Portugal under the project PTCD/CTM/101033/2008. S. Rout also acknowledges FCT for the postdoctoral grant (Ref. No. SFRH/BPD/64390/2009). | P1 35 |
| 17:00 | Role of a surface chemical treatment on the optical properties of SiNWs fabricated by single-step metal-assisted chemical etching Authors : I. Leontis and A. G. Nassiopoulou Affiliations : NCSR Demokritos, Institute of Microelectronics (IMEL), Terma Patriarchou Grigoriou, Aghia Paraskevi, 153 10 Athens Greece. e-mail: A.Nassiopoulou@imel.demokritos.gr Resume : SiNWs fabricated from p+ Si by a single-step metal assisted chemical etching (MACE) process in an HF/AgNO3 solution [1] were characterized by photoluminescence (PL) measurements, Fourier transform infrared (FT-IR) spectroscopy and reflectance and ultraviolet (UV) absorption measurements, in comparison with scanning and transmission electron microscopy (SEM, TEM) characterization. Measurements were performed after successive chemical treatments of the samples and it was demonstrated that the surface of the SiNWs is porous and composed of very tiny Si nanostructures that are responsible for their light emitting properties. The PL peak is broad, with a maximum in the red spectrum. After Piranha and HF treatment, the PL peak is blue-shifted and it gradually disappears, demonstrating that the PL origin is from Si nanostructures from the porous SiNW surface. The nanocrystals are reduced in size with the chemical treatment, causing the blue shift of the PL, and they disappear after successive chemical treatment cycles, leaving the SiNW surface very smooth. FT-IR, absorption and reflectance spectra were used to study the reflectivity/absorption properties of the samples, as well as their surface chemistry. PL decay times were also measured and the corresponding results will be discussed.
[1] A. G. Nassiopoulou, V. Gianneta, and Ch. Katsogridakis, Nanoscale Research Letters, vol. 6, 657, (2011) | P1 36 |
| 17:00 | Effect of Gd doping on the magnetic and transport properties of ZnO thin films Authors : S. Venkatesh1, Mahdieh Yousefi2, Neil Alford2 and Iman. S. Roqan1 Affiliations : 1.Materials Science and Engineering, Physical Sciences and Engineering division King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; 2.Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom Resume : ZnO based DMS materials are potential candidates for future spintronic devices [1]. The doping of Gd into GaN was reported to produce a high magnetic moment (~ 4000 µB/Gd) [2]. There is, therefore a strong motivation to attempt to dope Gd in ZnO. We have prepared ZnO targets with 0.5wt% and 1.0 wt% Gd and have prepared Gd doped ZnO thin films by pulsed laser deposition (PLD) on sapphire substrates at different Oxygen pressures. X-ray diffraction patterns (-2 scan) confirm that all the films were grown along the c-axis of the hexagonal Wurtzite structure. Gd 1.0wt % doped ZnO thin film deposited at 100mTorr of O2 was ‘n’ type and exhibited ~ 5% of negative magneto-resistance (MR) at 5 K. Gd 0.5 wt% doped ZnO deposited at 5 mTorr of O2 was also ‘n’ type and did not exhibit any any MR effect even at low temperature. Gd 0.5wt% doped ZnO thin film deposited at 25 mTorr of O2 showed ‘p-type’ conductivity with a hole concentration of 7.4 x1021cm-3. This value is similar to that observed in As doped ZnO [3]. A nonlinear field dependence of the resistivity, observed below 50 K with a 14% of negative MR at 5 K, suggests an enhancement of the magnetic ordering below 50 K. The role of Gd doping and O2 pressure in determining the carrier type and magnetic ordering are discussed based on the percolation effect and point defects; mainly oxygen vacancies.
References:
1) T. Dietl, H. Ohno, F. Matsukura, J. Cibert, D. Ferrand, Science, 287 (2000) 1019
2) S. Dhar, O. Brandt, M. Ramsteiner, V. F. Sapega, and K. H. Ploog, Phys. Rev. Lett. 94 (2005) 037205.
3) Y. R. Ryu, S. Zhu, D. C. Look, J. M. Wrobel, H. M. Jeong and H. W. White J. Crystal Growth 216 (2000) 330 | P1 37 |
| 17:00 | Physical properties of mixed oxides ZnO-In2O3 by ultrasonic spray Authors : F. Ynineb(a), A. Hafdallah(a), M.S. Aida(a)*, N. Attaf(a), J. Bougdira(b), H. Rinnert(b), S. Rahmane(c) and W. Daranfed(a) Affiliations : (a) Laboratory of Thin films and Interface, Exact Faculty of Science, Department of Physics, University Mentouri of Constantine 25000 Algeria. (b) Institute Jean Lamour UMR 7198, Department CP2S University of Nancy France. (c) Laboratoire de chimie appliqu?Universit?e Biskra, BP 145 RP, 07000, Alg?e. Resume : Transparent conducting oxides (TCOs) have the unique feature of combining optical transparency in the visible region with metal type electrical conductivity. There is still a need to have TCOs with better optimized opto-electronic properties. Very little works were related to the binary oxides in thin films like ZnO-SnO2, ZnO-In2O3, SnO2-In2O3, TiO2-In2O3… etc. This paper focus on (ZnO-In2O3) thin films were prepared by ultrasonic spray deposition with the molarity 0.1mol/l, and an atomic ratio of In/(In Sn) vary from 0 to 100%, on the well cleaned glass substrates. The resulting films were characterized by means of X-ray diffraction, Scanning electron microscopy analysis, UV-visible spectrophotometer and conductivity measurement. The analysis of the transmittance spectra allows us to deduce the films thicknesses and optical gaps. The values of the effective gap were found to be between 3.2 to 3.93 eV. X-ray diffraction analysis shows that the deposits have a preferential growth along the c-axis of hexagonal structure. And the electrical conductivity, calculated from transport measurement in a two probes coplanar structure, confirmed the increase of the electrical resistivity with mixtures to a value in the range of 38.10-1 (Ωcm)-1. In addition, the higher figure of merit (Fm= σ.T.d) of deposited films is obtained at 100 at.% which reveal the best film quality. | P1 38 |
| 17:00 | Growth and characterization of epitaxial ALD ZnO layers Authors : Zs. Baji, Z. L?di, M. Fried, Zs. Horv?, B. P?, I. B?ony Affiliations : Research Centre for Natural Sciences, Institute for Technical Physics and Materials Science P.O.B. 49, H-1525 Budapest, HUNGARY Resume : Abstract
The aim of this work is the growth and characterization of epitaxial ZnO onto GaN and c-sapphire substrates by means of Atomic Layer Deposition (ALD).
ZnO has attracted great attention recently because of its versatility in a number of applications, such as sensors and photovoltaic devices. It can be doped with aluminium to increase its conductivity, and be used as transparent conductive oxide layer.
ALD is a versatile method to deposit ZnO onto different substrates with the advantage of possible coverage of structured surfaces (cavities, grooves etc.) for sensoric purposes. However it is important to note that ALD films are typically of polycrystalline character.
Recently ordered arrays of hydrothermal ZnO nanowires were deposited by Erd?yi et. Al. [1] onto different structured surfaces. The alignment, crystal structure, and geometry of the NW arrays were dictated by the crystal structure of the underlying ZnO, and single crystal or epitaxial seed layers were preferred.
We have deposited ZnO layers on Si, GaN and sapphire substrates, and found completely different layer morphologies. Epitaxial growth is found possible both on GaN and sapphire with a proper tuning of the deposition parameters
ZnO layers were deposited in a SUNALE type ALD reactor. Doping was achieved by introducing various amounts of TMAl precursor pulses into the sequence of DEZn pulses. The deposition temperature varied between 120 and 300°, the amount of doping between 0 and 5 at%.
The crystal structure was determined by XRD. Epitaxial character of the layers is proved by cross-sectional TEM and HRTEM microscopy. The samples were characterized by spectroscopic ellipsometry (SE) as well as using Cauchy evaluation method.
Effects of substrate preparation, substrate temperature, pulse length on the properties of the epitaxial layers will be demonstrated.
[1.] R. Erdelyi et. al., Investiagations into the Impact of the Template Layer on ZnO Nanowire Arrays Made Using Low Temperature Wet Chemical Growth, Crystal Growth and Design, Vol. 11(6), pp. 2515-2519, 2011 | P1 39 |
| 17:00 | Chemical routes to In2O3 and Ga2O3 thin films for TOS applications Authors : Harish Paralai, Malte Hellwig, Anjana Devi Affiliations : Inorganic Materials Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany Resume : Transparent oxide semiconductors (TOS) are among the new materials that have recently attracted interest as active channel layers in transistors for applications in unconventional electronic products such as printable radio frequency identification tags (RFIDs), transparent and flexible displays, smart windows, sensors etc. because of their high carrier mobility and high optical transparency. Metal oxides are exciting class of TOS materials, for e.g. ZnO, Ga2O3, In2O3 and their alloys such as InGaO, InZnO, and GaInZnO are attractive candidates for TFTs with high electron mobilitites. In this presentation, the application of molecular precursors for the development of In2O3 and Ga2O3 layers on a variety of subsrates by metalorganic chemical vapor deposition (MOCVD) will be discussed. The structure, morphology and composition of the films were investigated by means of several techniques that include XRD, SEM, AFM, RBS and XPS. The optical properties of the as-grown layers have been studied using UV-Vis, PL and Ellipsometry measurements. Stoichiometric thin films of In2O3 and Ga2O3 exhibiting a high degree of transparency were obtained and the adopted chemical routes for film processing seem to be one viable route to get high quality layers with the new generation of In and Ga precursors. | P1 40 |
| 17:00 | CUxS THIN FILMS: MAIN PROPERTIES AND DEVICE APPLICATION Authors : • C. Nunes de Carvalho, ○ G. Lavareda, ♦ P. Parreira and *• A. Amaral Affiliations : Departamento de Ciência dos Materiais, FCT-UNL, Quinta da Torre, 2825-114 Caparica, Portugal; • ICEMS and * Departamento de Física, IST-UTL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; ○ CTS, FCT-UNL, 2825-114 Caparica, Portugal; ♦ SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK. Resume : CuxS thin films, 30 nm thick, are deposited at room temperature by vacuum thermal evaporation of sulfur-rich powder mixture, Cu2S:S (50:50 wt.%). The CuxS films are deposited at very low deposition rates (0.1-0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of CuxS films main properties (optical, electrical and surface morphology) under mild post-annealing in air at 270 C, from 255 up to 345 s, is studied. The as-deposited CuxS thin films are found to be very conductive and the annealed films found their electrical resistivity increased with annealing time (from 10-3 to 10-2 ohm.cm). Although the as-deposited films show inconclusive type of carriers (n or p-type), after the annealing treatment these films exhibit conclusive p-type conduction. SEM characterization, in order to verify possible changes in the surface morphology of the films due to annealing treatments, will be made. The application of these films in a TFT structure is also made and, consequently, the type of conduction in these films analyzed. The I(V) characteristics of CuxS based TFTs show that the conductivity in these films is mainly due to p-type charge carriers. | P1 41 |
| 17:00 | Hydrothermal growth of horizontal ZnO nanowires for sensor applications Authors : Khánh NQ,Lukács I, Volk J, Kurunczi S, Safrán Gy, Erdély R, Fülöp E, Szabó Z, Vondervisz F* Affiliations : HAS Research Center for Natural Sciences, 1025 Budapest, Pusztaszeri u. 59-67, Hungary *University of Pannonia, Faculty of Information Technology, 8200 Veszprém, Egyetem u. 10, Hungary Resume : Zinc oxide, as a biocompatible, wide band gap semiconductor is a very promising candidate material for sensor applications. One of its advantages is the ability to grow ZnO nanowires with high aspect ratio, which increases the sensitivity of the nanowire based sensor via the high surface to volume ratio. To this end, the ability to selectively grow lateral ZnO nanostructures will be an important development since these laterally orientated nanostructures constitute the very basic building blocks for the realization of integrated nanoscale devices on a planar substrate. In our present work metal contact layer has been utilized as a cover on top of the seed layer to promote the growth of horizontal ZnO multi-NWs by hydrothermal route at relatively low temperature. Long horizontal nanowires with diameter of 40-60 nm have grown on the surface of the substrate, and thus are able to provide electrical paths over the gap of several micrometers. Crystal structural and electrical characterizations of the achieved nanowires have been carried out and discussed. Demonstration of such device for sensor applications will be also presented. | P1 42 |
| 17:00 | Optical and electrical properties of ZnO:In thin films prepared by spin coating technique Authors : M. Hajiri1, F. Ghribi1,2, A. Alyamani2, L. El Mir1,2,* Affiliations : 1Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Gabes University, Faculty of Sciences in Gabes, Gabes, Tunisia. 2National Nanotechnology Research Centre, KACST, Riyadh, Saudi Arabia. 3Al-Imam Muhammad Ibn Saud University, College of Sciences, Department of Physics, Riyadh 11623, Saudi Arabia. Resume : Zinc oxide doped indium (IZO) thin films have been prepared on glass substrate using sol–gel spin-coating method with different doping concentrations from 1 to 5 at.%. The sol was prepared using 2-methoxyethanol and monoethanolamine (MEA, C2H7N14) as a solvent and stabilizer, respectively. Zinc acetate dehydrate (Zn (CH3COO)2 .2H2O) was used as a precursor and indium chloride (InCl3) as a doping source. The X-ray diffraction result indicates that the ZnO film has the polycrystalline structure with average grain size varied from 26.5 to 38.7 nm. An increasing of doping concentration increases the crystallinity of the thin films. The optical transmittance spectrum indicates the average transmittance higher than 90% in visible region. The band gap energy is about 3.3 eV. The refractive index and the extinction coefficient were calculated by envelope method. From the four-point technique, the lowest sheet resistance was 0.303 MΩ/sq corresponding to indium concentration of 2 at.%. The obtained thin films are promising for solar cells and gas detection. | P1 43 |
| 17:00 | Contamination in single Co implanted ZnO nanowires investigated by hard X-ray nanoprobe Authors : M. H. Chu 1, J. Segura-Ruiz 1, G. Martinez-Criado 1, I. Snigireva 1, S. Geburt 2, and C. Ronning 2 Affiliations : 1 European Synchrotron Radiation Facility, Experiments Division, 38043 Grenoble, France; 2 Institute of Solid State Physics, University of Jena, D-07743 Jena, Germany Resume : Co doped ZnO nanowires (NWs) have been widely investigated in recent years as one of the most promising dilute magnetic semiconductors (DMSs) for potential applications in spintronic nanodevices. However, the origin of the room temperature ferromagnetism observed in this DMS is not clear, and the question whether this behavior is intrinsic or extrinsic remains open. The reduced density of defects observed in the NWs and the good control of their doping, allow to study in more detail this issue. However, the presence of unintentional doping into the NWs, coming from the growth or implantation process can limit these studies. So far, there are only few reports on the presence of contamination in Co doped ZnO NW. Furthermore, the low sensibility for the detection of trace elements strongly limits the study of unintentional doping. In this work we have characterized single Co implanted ZnO NWs by X-ray fluorescence (XRF) nanoprobe. Elemental maps showed homogeneous Zn and Co distributions along the entire wire within the length scale of the beam size, without any signature of metallic clusters. The high energy and photon flux available in our beamline allow us to study the presence of magnetic and non-magnetic dopant elements inside the NWs and their spatial distribution. | P1 44 |
| 17:00 | Synthesis of bismuth oxide films by thermal oxidation of bismuth nano-droplets deposit on GaAs substrate Authors : H. Fitouri, R. Boussaha, A. Rebey and B. El Jani Affiliations : Université de Monastir, Unité de Recherche sur les Hétéro-Epitaxies et Applications Faculté des Sciences de Monastir, 5000 Monastir, Tunisia Resume : Bismuth oxide has attracted considerable attention due to its interesting characteristics, such as the large values of the energy band gap, high refractive index and dielectric permittivity, besides remarkable photoconductivity and photoluminescence. This oxide material is promising for development of various modern technologies of solid state device. In this work, bismuth oxide films were prepared by dry thermal oxidation of bismuth nano-droplets deposit on GaAs substrate by metalorganic vapor phase epitaxy. The oxidation process of Bi nano-droplets consists of a heating from the room temperature to a different oxidation temperatures (350, 500, 600°C) with a temperature rate of 14°C/min. The annealing duration was fixed to 30 min. The presence of oxygen in the annealed films was confirmed by energy dispersive X-ray measurements using a scanning electron microscope (SEM). The SEM images show that the density of Bi aggregates decreases and their size increases with increasing annealing temperature. The photoluminescence spectra under excitation at 325 nm shows a strong and broad emission centered at around 640-660 nm. The reflectance spectra of the films were studied in spectral domains ranged between 200 nm and 1200 nm. The results show that the thickness of the bismuth oxide increases with increasing annealing temperature. By fitting the reflectivity signal, we extracted the refractive index variation of bismuth oxide films as a function of the wave length. | P1 45 |
| 17:00 | Beta-phase Morphology in Ordered Poly(9,9-dioctylfluorene) Nanowire Arrays by using liquid-bridge-mediated nanotransfer moulding Authors : Jangmi Baek, Boram Cho, Kyung Sun Park, Kwan-Hyuck Yoon, Myung M. Sung Affiliations : Department of Chemistry, Hanyang university, Seoul, Korea Resume : An efficient method based in liquid-bridge-mediated nanotransfer moulding
(LB-nTM) is applied for fabrication of ordered Poly(9,9-dioctylfluorene) (PFO)
nanowire arrays with β-Phase morphology.
This process is a new direct nano-patterning method based on the direct
transfer of various materials from a mould to a substrate via liquid layer. PFO nanowire arrays are prepared under
ambient conditions via selective inking of polymer ink and transferring to various
substrates, such as glass, silicon and PET film. The formation of the β-phase morphology in the
resulting PFO nanowire array was evidenced by the presence of an absorption
peak at 435nm. With the collection
polarizer oriented parallel to the wire long axis, the PL emission was most
intense and an emission dichroic ratio, DRE, of 3.7 was determined. The nanowire array have been investigated by
scanning electron microscopy (SEM).
Also, we simply fabricated structure of device of ITO/PFO nanowire
arrays/Al and the electroluminescence spectra were recorded at various applied
voltage. | P1 46 |
| 17:00 | Synthesis, structural characterization and ferroelectric properties of the barium titanate nanofibers Authors : Pedro Sá, Dmitry Isakov, Igor Bdikin, Anabela G. Rolo, Bernardo Almeida and Etelvina de Matos Gomes Affiliations : University of Minho, Center of Physics, Campus de Gualtar, 4710-059 Braga, Portugal; Department of Mechanical Engineering & TEMA, University of Aveiro, 3810-193 Aveiro, Portugal Resume : The nanofibers of barium titanate (BaTiO3) present a complex structure of stacked nanoparticles (with 30–80 nm size) forming continuous fiber-like arrangement. They are formed by sintering the electrospun fibers at high temperatures. The fiber-like arrangement of the barium titanate present particular interest since this structure can potentially serves as unit for a ferroelectric random-access memory and nanoelectromechanical systems.
In BaTiO3, for small particle sizes (below ~20 nm) the high-temperature cubic phase is retained at room temperature and the formation of the tetragonal (ferroelectric) phase is hindered, what can significantly limit their possible applications. In this work, the synthesis routine to obtain nanofibers of polycrystalline BaTiO3 with the tetragonal structure is presented. The temperature dependent second harmonic generation studies shows the presence of the paraelectric-ferroelectric phase transition at 120ºC. The ferroelectric properties have been studied by using piezoelectric force microscopy. The influence of the post-deposition annealing treatment on the ferroelectric and non-linear optical properties of the BaTiO3 nanofibers is also discussed. | P1 47 |
| 17:00 | SOME FEATURES OF DIELECTRIC PROPERTIES OF NANOCOMPOSITES ON BASE OF CdS/ PVA OBTAINED BY USE OF SUCCESSIVE IONIC LAYER ADSORPTION AND REACTION Authors : M.B.Muradov,S.Ismat Shah*, K.A.Yusifova, G.M.Eyvazova,R.K.Mammadov,A.M.Maharramov, A. Kokovezch** K.Kordas*** Affiliations : Department of Physics, Baku State University, Z. Khalilov str. 23, Republic of Azerbaijan *Materials Science and Engineering Dep.,University of Delaware, USA, **Dept. of Applied and Environmental Chemistry, University of Szeged, Hungary ***Microelectronics and Materials Physics Labs University of Oulu, Finland Resume : Introducing semiconductor nanoparticles into polymer matrix volume changes physico- chemical properties of the system. Furthermore, the physic chemical properties of the system will be under an influence of the effects of interaction of nanoparticles with polymer matrix, inter phase phenomena polymer- nanoparticle. With the help of SILAR method nanoparticles of chalcogenide semiconductors in a volume of the different polymer matrixes have been formed. As a rule, in these experiments as solutions were used as water solutions of electrolytes. However, in some cases it is expedient to use waterless solutions of electrolyte. Expediency of a type of electrolytic solution used depends on a property of polymer, character of interaction polymer-solution of electrolyte. In the present work there have been investigated dielectric properties of of nanocomposites cadmium sulfide /polyvinyl alcohol (CdS/PVA) obtained with the help of SILAR from solutions of electrolyte of ethylene glycol.
Investigations of frequency dependence of the samples showed that dielectric permittivity of samples depend from temperatures and growth cycles. The character of distribution of nanoparticles depend on a quantity of growth cycles. A change in a number of cycles leads to changing the character distribution of nanoparticles in polymer. These factors also influence to means of dielectric permittivity of CdS/PVA nanocomposites.
This work was partially funded by FP7 NAPEP project № 266 600. | P1 48 |
| 17:00 | Facile nonhydrolytic sol–gel route to mesoporous mixed-conducting tungsten oxide Authors : G. Orsini, V. Tricoli Affiliations : University of Pisa Resume : Mesoporous, mixed-valence tungsten oxides were synthesized by a nonhydrolytic sol–gel method utilizing 1-butanol/tert-butanol mixtures as the gelling solvent. Composition of the alcohol
mixture influences the mesoporous characteristics of final products. By tuning synthesis and processing
conditions specific surface area up to 140 m2/g was achieved with a pore volume in excess of 0.5 cm3/g and fairly monodispersed pore-size around 18 nm. Presence of tungsten in W(V)-state besides
W(VI)-state, as revealed by XPS, determines the existence of oxygen vacancies in the structure. This
confers important n-semiconducting characteristics upon the materials as demonstrated by EIS.
Oxygen-vacancy concentration can effectively be varied by tuning conditions of thermal treatment,
with strong impact on the electrical properties. Electron conductivity of ca 20 S/cm was registered at
room temperature for oxide subjected to treatment at 500°C. Upon wetting or humidification, these
materials also acquire remarkable proton-conduction characteristics. Proton conductivity in excess of
15 mS/cm was measured at room temperature. As a result, these mesoporous oxides do exhibit
concurrent electron and proton conduction properties under humidified conditions. Apparently, the
porosity characteristics accompanied by mixed electron/proton conduction, make these materials
especially appealing as conducting, mesoporous substrates utilizable in a variety of electrochemical
systems, including fuel cells. | P1 49 |
| 17:00 | SiO2 encapsulated Au nanowires produced by oxidation of patterned planar Si:Au paths Authors : K. Maksimova1, P. Gaiduk2 and A. Zenkevich3 Affiliations : 1Immanuel Kant Baltic Federal University, 236041, Kaliningrad, Russia; 2Belorussian State Univeristy, Minsk, Belarus; 3NRNU “Moscow Engineering Physics Institute”, 115409, Moscow, Russia Resume : The development of emerging electronic devices dictates the need for the synthesis of the novel nano-materials, their physical characterization and eventual functionalization as active elements. Metal nanowires and nanowhiskers are particularly promising building blocks for multifunctional devices. In this contribution, we report on the novel approach for the synthesis of planar metal nanowires encapsulated in dielectric shell. It has been previously reported [1] that in case of a noble metal (e.g., Au), the oxidation of a diluted Si:Me mixture results in the metal segregation inside the silicon oxide and leads to the formation of Me nanostructures embedded in SiO2 shell. The suggested process for the formation of encapsulated metal NWs consists of the deposition of the alloyed Si:Me thin film with predefined composition and thickness, its surface passivation by SiNx cap, nanopatterning by e-beam lithography and further lateral oxidation of the patterned paths. Rutherford backscattering spectrometry is used to determine the actual composition ratio Si:Au ~ 20:1 and thickness (~20-40 nm) of the initial alloyed Si:Au films produced by pulsed laser deposition on pre-oxidized Si substrates. Thermal oxidation at T≈ 550-650º C in dry O2 is used to process the lithographically patterned ~100 nm wide Si:Au paths of various shapes. The formation of planar Au NWs encapsulated in SiO2 is evident from the plan-view transmission electron microscopy analysis.
1. A. Novikau et al. NRL 6 151 (2011). | P1 50 |
| 17:00 | Effect of nanoparticle morphology on thermal conductivity and rheology of Zinc Oxide nanofluids. Authors : N.Nikkam, M. Saleemi, M. S. Toprak , S. P. Singh, M. Muhammed Affiliations : Functional Materials Division, Royal Institute of Technology (KTH) , SE 16440 Kista-Stockholm, Sweden Resume : Nanofluids are stable dispersions of engineered nanometer-sized particles which have shown potential to enhance heat transfer properties. Nanoparticle morphology might influence the heat transport properties of the nanofluid. In this work our aim is to investigate the influence of nanoparticle morphology in the heat transfer and rheological properties of ZnO nanofluids. ZnO nanoparticles and nanorods were synthesized and dispersed in ethylene glycol, as the base fluid, to obtain nanofluids with different percentages of nanoparticle loading. Ultrasonic agitation was used for obtaining a stable suspension and the use of surfactants was avoided. The concentrations of ZnO nanofluids were varied between 1 wt% and 3 wt%. The physicochemical properties of nanofluids were characterized by using various techniques including particle size analyzer, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The thermal conductivity of prepared nanofluids were measured by Transient Hot Wire (THW) method and our finding on the physicochemical, transport and rheological properties of the ZnO nanofluids, containing nanoparticles with different morphology, are presented in detail. | P1 51 |
| 17:00 | The Origin of Bimodal Size Distribution of Silicon Nanocrystals Synthesized in a Remote Expanding Thermal Plasma Authors : I. Dogan1, S. Weeks2, S. Agarwal2, M.C.M. van de Sanden1 Affiliations : 1. Department of Applied Physics, Eindhoven University of Technology, The Netherlands; 2. Department of Chemical Engineering, Colorado School of Mines, Golden, CO, USA Resume : Unique properties present in confined Silicon Nanocrystals (Si-NCs) like size dependent luminescence and improved charge storing have generated interest in a variety of different applications. For successful applications, the main issues on Si-NC synthesis are size control, surface engineering and high throughput processing. Among these points, the amount of throughput is highly critical for large scale applications however, this is not possible to achieve with current production techniques. Our research goal is to show that it is possible to fulfill these demands with a novel route by using the remote expanding thermal plasma (ETP) technique. ETP is observed to result in a very high throughput of 25 mg/minute. However, we observed a bimodal size distribution of small (3-10nm) and large (40-140 nm) NCs due to the reactor geometry. To move towards a better control of the size distribution a geometrical separation route is used. Results of experimentation indicate the suppression of large NC growth, however isolated large NCs are still observed. Further efforts to eliminate large NCs focus on the use of pulsing silane into the reactor on the millisecond range with the aim of consuming the silane on a timescale faster than that of large NC growth, thus inhibiting their formation. First results show that growth of NCs is nucleation controlled. Furthermore, larger NCs are not the result of coalescence of smaller particles, as evidenced from TEM measurements. | P1 52 |
| 17:00 | Structural, morphological and electrochromic properties of Niobium Oxide coatings obtained by two low-cost deposition techniques Authors : R. Romero, A.Villalba, D. Leinen, J.R. Ramos-Barrado, F. Martin Affiliations : Laboratorio de Materiales y Superficie (Unidad asociada al CSIC). Dptos Física Aplicada I & Ingeniera Química, Facultad de Ciencias, Universidad de Málaga. España Resume : This work presents a comparative study between Nb2O5 coatings obtained by two low cost deposition techniques, as Spray Pyrolysis and Spin Coating onto ITO substrate are. The coatings were deposited homogeneously over an area of 6 cm2. NbCl5 has been used as precursor. Due to its high instability in aqueous medium, the precursor solution was carried out with different ratios alcohols-distilled water. The deposition parameters have been optimized for both deposition techniques and the convenience of post-annealing has been studied in terms of structural, chemical and morphological properties of coatings. The coloration efficiency, lithium ions diffusion coefficient and charge densities are estimated from cyclic-voltammetry, chronoamperiometric and in-situ optical measurements. The coatings exhibit a dark blue coloration under lithium insertion with a decrease of 50% of transmittance in the visible region while cathodic charges densities exchanges are about 3mC/cm2. The kinetics and the reversibility of electrochemical process were also studied for the coatings by electrochemical impedance spectroscopy showing a dependence on the applied potential during the redox process. Finally some coatings were assembled in a solid electrochromic device with a sandwich configuration, where Nb2O5 coatings was employed as electrochromic materials and polyvinylpyrrolidone with LiClO4 as polymer electrolyte. | P1 53 |
| 17:00 | Analysis of Surface Charging Effects in passivated AlGaN/GaN HEMTs Authors : M. GASSOUMI1, H. MOSBAHI1, B. GRIMBERT2, C GAQUIERE2, and H. MAAREF1 Affiliations : 1Laboratoire de Micro-Optoélectroniques et Nanostructures Faculté des Sciences de Monastir, Université de Monastir 2 Institut d’Electronique de Microélectronique et de Nanotechnologie IEMN, Université des Sciences et Technologies de Lille, Avenue Poincaré, 59652 Villeneuve d’Ascq Cedex, France Laboratory of Micro-Optoelectronic and Nanostructure, university of Monastir, Monastir 5000(Tunisia): Resume : AIGaN/GaN heterostructure transistors show potential in high-frequency high-power applications. Si3N4 passivation of the surface of the devices has been implemented to improve the RF performance of the device and elimination of the RF power slump. This passivation technique is now widely used in device fabrication, but the mechanism of the action of the passivation is not clearly understood.
However the real source of the slump is still unclear. In this Letter we report an effort to establish the result of the action of passivation on the device characteristics.
The effect of SiN passivation of the surface of AlGaN/GaN transistors is reported. Conductance deep level transient spectroscopy (CDLTS) measurements were performed on the device before and after the passivation by a SiN film. The CDLTS spectra from these measurements showed the existence of electrons traps on the surface of these devices.
Keywords: AlGaN/GaN, Traps, HEMTs passivated, CDLTS, Surface traps. | P1 54 |
| 17:00 | TiO2 micropatterning by unconventional UV lithography Authors : Catalin Parvulescu1, Elena Manea1, Paul Schiopu2 Affiliations : 1)National Institute for Research and Development in Microtechnologies, IMT-Bucharest, Romania 2)University Politehnica of Bucharest, Faculty of Electronics, Telecommunications and Information Technology Resume : We present a novel process for the manufacture of microstructures of anatase TiO2 thin film by useing unconventional UV-lithography. Glass wafer substrate was coated with positive photoresist that has been micropatterning through a mask by UV-radiation. After that a Ti thin film of 50nm was been deposied by dc sputtering (1.82*10-3 Pa, 100 W) on the entire surface (similar lift-off technique). Novelty consists in coating with another thin layer of positive photoresist on titanium layer that will be exposed to UV radiation through the same mask, utilizing this layer as a mask for local anodization of titanium. Finally we obtained titanium oxide through electrochemical anodization of titanium using a mixture based on NH4F as electrolyte. Lift-off process was used to remove photoresist film by immersion in solvent such as acetone and TiO2 selective patterns has been obtained.
A TiO2 thin film fabricated by this method has no cracks and the feature edge was much higher than that of the micropattern obtained by other method. | P1 55 |
| 17:00 | Enhanced Diamond Nucleation by Surface Plasma Pretreatments Authors : P. Pobedinskas (1), G. Degutis (1), W. Dexters (1), C. De Dobbelaere (1), S.D. Janssens (1,2), J. D'Haen (1,2), A. Hardy (1,2), M.K. Van Bael (1,2), K. Haenen (1,2) Affiliations : (1) Hasselt University, Institute for Materials Research (IMO), Wetenschapspark 1, B-3590 Diepenbeek, Belgium; (2) IMEC vzw, IMOMEC, Wetenschapspark 1, B-3590 Diepenbeek, Belgium Resume : The growth of CVD diamond on non-diamond substrates requires artificial formation of diamond nucleation sites on the substrate's surface. Current state-of-the-art seeding procedures using water-based colloidal solutions of ultra dispersed nanodiamond (ND) powder, have made the deposition of closed films of less than 100 nm on 2D and 3D structures easily attainable. While deposition times are reduced, an acceptable surface roughness is retained. As will be shown, the substrate surface charge and ND particles' zeta-potential are the most important factors that determine the nucleation density.
In this work various surface pretreatments for enhanced diamond nucleation are presented. The surface of silicon and polycrystalline AlN thin films are exposed to different gas discharge plasmas (Ar, CF4, H2, N2, O2) before the application of the seeding procedure with monodispersed ND. The seeding density was analyzed by atomic force microscope. It is shown that surface modifications strongly influence the nucleation density. The different surface groups and plasma-induced surface roughening change the interaction force between the ND particles. A correlation is observed between the seeding density and the adhesion force of particles to the rough surface described by the Rabinovich model. The versatility of these procedures allow to successfully deposit the densely packed 100 nm thick NCD films on piezoelectric materials like AlN, opening up routes for diamond-based acoustic devices. | P1 56 |
| 17:00 | Porous silicon conversion into porous copper membrane by displacement liquid technique Authors : Hanna Bandarenka1, Sergey Redko1, Vitaly Bondarenko1, Paolo Nenzi2, Marco Balucani2 Affiliations : 1 Department of Micro and Nanoelectronics , BSUIR, Minsk, Belarus; 2 Department of Information Engineering, Electronics and Telecommunications, University “Sapienza", Roma, Italy Resume : Porous Cu membranes of 8-20 um were converted from the porous Si (PS) template by the liquid displacement technique. Boron doped c-Si (111) wafers of 0.3 Ohm∙cm resistivity were used as initial substrates. PS layers were formed by electrochemical anodization of Si in a solution of HF (45%), DMSO and С3Н7ОН at 7 mA/cm2 for 85 min. The structure of PS represented the ordered channels of the mesopores partially filled with the spongy like nanoporous Si. Cu porous membrane was fabricated by immersion of PS for 180 min in a Cu sulphate aqueous solution with additions of HF and C3H7OH provided the continuous displacement of the PS skeleton with Cu and good reagents exchange throughout the pores. After complete PS conversion into metal the Cu film was immediately separated itself from the substrate. The morphology and the structural parameters of the Cu membrane were studied by SEM. The membrane consisted of two layers of Cu structures. The upper layer contacted with the solution during displacement process. It represented the array of large spherical crystals. The bottom layer has the spongy-like structure. The elemental analysis was performed with EDX spectroscopy. Presence of the oxygen was found among the Cu atoms. Young modulus measurements of the Cu membrane were performed in air by means of a Perkin Elmer DMA8000 system at -100 °C and 100 °C. Strong anisotropy of the Cu membrane was revealed. It was stiffer in the direction parallel to the pores, that is perpendicularly to the plane of the membrane. The electrical conductivity of the porous Cu was 60-70% of bulk Cu. Two porous Cu films were used as electrodes for supercapacitor with liquid electrolyte. Three orders increase of capacitance for porous Cu electrodes was experimentally measured as compared with flat nonporous electrodes. Moreover, the Raman spectroscopy of the R6G molecules adsorbed on the surface of the Cu porous membrane has resulted in the surface enhanced signal observing.
This research was partially supported by the Belarusian Foundation for Basic Research under the Projects T10M-089 and T11OB-057 and by Rise Technology S.r.l. | P1 57 |
| 17:00 | Selective Growth and Characterization of a SnO2 nano-wire by employing DNA-templated Gold Nanoparticle chains Authors : Jinhee Heo, Hyung Jin Kim Affiliations : Korea Institute of Materials Science(KIMS);School of Information and Communication Engineering, Sungkyunkean University Resume : Recently, the Tin-oxide(SnO2) has been widely used in the fabrication of various gas(O2, CO, NOx) detecting sensor. Basically, the SnO2 is n-type semiconductor which has a wide band gap, about 3.99eV. Also, thin film of SnO2 has been known as a transparent electrode and it is applicable for a various electronic parts. Nowadays, research on SnO2 nano-wire characterization is very actively performed because it is able to realize a micro-sensor array with conventional Silicon processing. However, it isn’t easy to align a single SnO2 nano-wire on the specific site for the fabrication of integrated gas sensoer device. To achieve a high-performance gas-sensor with SnO2, we need to make integrated single SnO2 nano-wire 2 electrode devices. In this study, we employed DNA-templated alignment using a combination of molecular combing and surface-patterning techniques to form a Au nanoparticle chain as a catalyst. It is possible to obtain parallel and latticed nanostructures consisting of DNA molecules and thus DNA-templated Au nano-wires aligned at 400nm intervals.[1,2] After that, a single SnO2 nano-wire which had been synthesized on the Au nanoparticle by a thermal process.[3,4] By using the AFM probing technique, a Rh coated conducting cantilever can approach a single SnO2 nano-wire in nano scale and get the I-V curves with sweeping applied voltage between Au electrode and cantilever with a controlled concentration of Oxygen in measuring chamber to change the ionosorption rate. From the results of such experiments, we selectively grow SnO2 nano-wires and verified Oxygen detecting ability which would be necessary for the realization of micro-sensor array. | P1 58 |
| 17:00 | Fabrication and characterizations of zinc oxide nanowires for novel device applications Authors : S.R. Bhattacharyya, R. Ayouchi, and R. Schwarz Affiliations : Departamento de Física, Instituto Superior Técnico, 1049-001 Lisbon, Portugal Resume : One dimensional zinc oxide (ZnO) nanostructures constitute a new class of photoelectrodes for dye sensitized solar cells and piezoelectric components for energy harvesting. In order to put it into device applications, one must have a detailed idea about its optical and transport properties and the effect of surface states and defects in modulating them.
Zinc oxide (ZnO) nanowires with a length of ~ 600-1100 nm and a diameter of ~ 20-40 nm were deposited by a two-step wet chemical technique. The initial seed layer was deposited by pulsed laser deposition (PLD) on glass substrate, while the nanowires were grown on top of it by a modified solution growth method at low temperature. The films were characterized optically by measuring optical transmission using an ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometer and photoluminescence (PL), while structural studies were carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The transport properties within the samples were characterized by dark and photoconductivity measurements and by transient photocurrent response (TPC) technique. Steady-state photocurrent and PL measurements were carried out using a continuous 325 nm line of HeCd laser. The transient photocurrent decay measurement was carried out with a pulsed Q-switched (5 ns pulse) Nd:YAG 266 nm laser line. PL spectra showed broad orange-yellow and green peak at room temperature (300 K) and 80 K, indicating surface states and deep defects. The photocurrent was found to be orders of magnitude smaller than the dark current. The TPC measurements also indicated slow decay characteristics of multiple trapping consistent with reemission of carriers trapped in deep defect states. The results were correlated with the PL analysis to obtain meaningful information about the defects and optoelectronic processes within the material. | P1 59 |
| 17:00 | Scalable strategies for the synthesis of well-defined metal and oxide nanocrystals Authors : Pascal Lignier,* Ronan Bellabarba, Robert P. Tooze Affiliations : Sasol Technology (U.K.), Ltd, Purdie Building, St. Andrews KY16 9ST, United Kingdom Resume : The most promising methods for the preparation of well-defined metal and oxide nanocrystals are discussed.1 These methodologies could be applied to a wide range of elements. We present the main synthetic strategies and associated mechanisms to control monodispersity, size, morphology and structure of these nanomaterials which can adopt various shapes and structures. We also consider the scale-up of the production of these nanocrystals, which is crucial for a wide range of potential applications such as catalysis, photovoltaics, electronics, optics and electrocatalysis.
1 Lignier, P.; Bellabarba, R.; Tooze, R. P. Chem. Soc. Rev. 2012, DOI: 10.1039/C1CS15223H, advance article. | P1 60 |
| 17:00 | Synthesis and characterization of Ho doped ZnO thin films grown by sol-gel process Authors : M. Popa1, 2, G. Schmerber1, C. Ulhaq - Bouillet1, O. Ersen1, S. Colis1, A. Dinia1, L. Ciontea2, T. Petrisor2 Affiliations : 1 IPCMS, UMR 7504 CNRS, UDS-ECPM, 23 rue du Loess, B.P. 43, 67034 Strasbourg Cedex 2, France 2C4S, Technical University, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania Resume : The influence of different Ho concentrations (1, 3, and 5 at %) on ZnO thin films properties was studied. Ho doped ZnO thin films were synthesized by sol-gel method and followed by their structural, morphological, optical, and electrical characterizations. The morphology and the microstructure of these films were studied by scanning and transmission electron microscopies. X-ray diffraction revealed a würtzite structure of the samples, with a higher c cell parameter when the dopant concentration was increased. The optical transmission was always in the order of 90% in the visible range. The band gap energies of the samples, calculated from UV-Vis spectra, indicated a decrease of the energy by increasing the Ho concentration from 1 to 5 at %. Electrical measurements on these films gave resistivities as low as 4. 10-2 Ω.cm. | P1 61 |
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