Symposium : Q
Novel materials and fabrication methods for new emerging devices
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| 10:45 | Fabrication of conducting polymer devices for bioelectronics Authors : George Malliaras Affiliations : Department of Bioelectronics Centre Microélectronique de Provence Ecole Nationale Supérieure des Mines de Saint Etienne France Resume : Conducting polymers devices in the forms of electrodes, chemiresistors and transistors are being used in bioelectronics as means to sense/actuate biological events in an electrolyte. Examples include applications in neural interfaces, biosensors and tissue engineering. These applications often require fabrication on mechanically flexible substrates and over large areas, imposing strict limits on the deposition and patterning techniques used for device fabrication. The use of photolithography in the fabrication of these devices will be discussed and contrasted with ink-jet printing. Examples will be mainly drawn from neural interfaces. | 1 1 |
| 11:15 | ZnO nanowire based mechanical sensor for in vivo applications Authors : Róbert Erdélyi, János Volk Affiliations : 1. HAS Research Centre for Natural Sciences Institute for Technical Physics and Materials Science 2. University of Pannonia, Faculty of Information Technology Resume : One dimensional semiconducting ZnO nanostructures are considered as important building blocks for fabricating various nanodevices due to their unique electronic, optical and piezoelectric properties. Although ZnO nanowire (NW) and nanorod (NR) based light emitting diodes, laser diodes, sensors and resonators have been succesfully demonstrated, field effect transistors (FET) and energy converters are among the most studied devices as well. The talk will introduce a NEMS carrying the possibility of in vivo nanoforce sensing due to the electromechanical properties of a purpose positioned ZnO NR. The perpendicularly standing NR is contacted by two electrodes, and acts as a FET without using a common gate electrode. Here the gate is practically a lateral bending which controlls the current through the NR. The nanorod was grown wet chemically through an e-beam lithography generated cylindrical hole on a pulsed laser deposited single cristallyne ZnO layer on c-sapphire with a Pt middle layer. This seed layer provides low resistivity bottom contact and allows c-axis oriented epitaxial growth of the NRs. The bending modulus of such rods was determined by our well controlled combined in-situ static-dynamic mechanical test in a scanning electron microscope. The comparison of the two methods will be presented, as well as the first results of the testing of our integrated ZnO NR based nanoforce sensor. A novel solution for the upper contact using high conductivity p-type polymer, which provides strain dependent junction with ZnO NRs, will be also addressed. This work was supported by the National Development Agency grant TÁMOP-4.2.2/B-10/1-2010-0025. | 1 3 |
| 11:30 | Study of the influence of 10ο off-Si substrate on growth of β-SiC nanocrystals Authors : G. Deokar (1), M. D’angelo (1),C. Deville-Cavellin (1,2) Affiliations : 1. Institut des Nanosciences de Paris, UMR7588 du CNRS and University Pierre et Marie Curie – Paris, France 2.Faculty of Science and Technology, University Paris12-Val de Marne, 61 av.General De Gaulle, 94010 Créteil, France Resume : SiC nanocrystals (NCs) below 10nm size are known to show luminescence due to quantum confinement effect 1. Orderly growth of the luminescent SiC NCs could be used to fabricate light emitting displays and field emitters.
Here, we show heteroepitaxial, β-SiC NCs growth on Si(001) substrate. For that a simple method was used 2 : the NCs were grown by heating silica layer on Si samples in few hundreds of mbar of CO2 at 1100 ο C for 1 to 12 hours. High resolution scanning electron micrographs have evidenced formation of isolated, plus shaped NCs on both 10ο off-Si and Si without miscut. Nucleation density (ND) estimation showed over one order of magnitude enhancement in the ND of the NCs for 10ο off-Si as compared to the ND for on-Si. The NCs size and the ND estimation for various treatment times and pressures, showed that NCs size and the ND can be controlled by these two parameters. For the 10ο off-Si cross-section TEM showed that the NCs nucleation occurred at the steps edges. These NCs were preferential aligned along step edges (in the (1-1 0) direction). Thus the surface atomic steps are playing vital role in enhancement of nucleation and alignment. Further work to obtain optimized parameters for fabrication of one or two dimensional ordered arrays of SiC NCs is in progress. This investigation illustrates the possibility of fabrication of self organized SiC NCs.
1 J. Botsoa et.al., Appl Phys Lett 92 (17) 2008
2 O. Krafcsik et.al. J Electrochem Soc 149, G297, 2000 | 1 4 |
| 11:45 | Deformable QR Codes with Shape Memory Functionality Authors : Thorsten Pretsch, Melanie Ecker Affiliations : BAM Federal Institute for Materials Research and Testing, Division 6.5, Polymers in Life Science and Nanotechnology Resume : Shape memory polymers (SMPs) have the potential to serve as valuable technology platform for a safe way of information storage and release. When integrating small amounts of dye molecules into SMP surfaces, the contrast gets high enough for decoding engraved Quick response (QR) codes by means of a scanning and decoding device. Subsequently, thermo-mechanical functionalization (programming) can be utilized to stabilize the polymer in a new shape with non-decodable QR code information. As a result of triggering the shape memory effect, the mostly complete recovery of the polymer surface takes place. As such, the QR code can again precisely be read out.
The successful realization of this new technological concept will be reported. This includes the implementation of polymeric prototypes, employment of different thermo-mechanical functionalization strategies and setting of evaluation criteria when investigating the shape memory performances. On the basis of our experimental results, tagging products with such information carriers is assumed to be a helpful tool for the purpose of secure one-time identification. | 1 5 |
| 12:00 | Lunch | |
| 13:30 | Ultrasonic Spray-Assisted Vapor-Deposition Method as a Cost-Effective and Environmental-Friendly Technology for Fabrication of Novel Devices Authors : Jinchun Piao, Sam-Dong Lee, Shigetaka Katori, Takumi Ikenoue, Kentaro Kaneko, and Shizuo Fujita Affiliations : Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan Photonics and Electronics Science and Engineering Center, Kyoto University, Kyoto 615-8520, Japan Resume : One of the important targets for the recent novel devices is directing to save energy, as is well demonstrated by power devices and solar cells. The careful consideration of the cost and energy necessary for the device fabrication is also a key for how amount of energy can be saved by the device. A non-vacuum and solution-based fabrication method is a basic requirement for the novel process of thin film formation. In this presentation we show potential of a ultrasonic spray-assisted vapor deposition method (mist deposition method) for the fabrication of organic and inorganic thin films capable of contributing to emerging devices.
The basic concept of mist deposition method is to utilize mist particles of solution source being subjected to ultrasonic power as a reaction source transferred like a gas source. We can use inexpensive and safe source precursors and reduce the energy necessary for the film formation. This technology have allowed the deposition of a variety of material thin films including transparent oxide thin films (TCOs) such as ZnO and ITO, insulators such as Al2O3 and SiO2, single-crystalline oxide semiconductors such as ZnO, Ga2O3, and In2O3, and organic thin films such as organic LED and solar-cell materials.
We will show the properties of thin films fabricated by the mist deposition method. Based on the fundamental film formation data, our research has been extended to fabricate actual devices. The results will also be included in the presentation at the symposium. | 2 6 |
| 13:45 | Electrophoretic deposition of shape-controlled titanium dioxide nanocrystals Authors : Vincent Jouenne, Jean-Luc Duvail, Mireille Richard-Plouet, Luc Brohan Affiliations : Institut des Matériaux Jean Rouxel, UMR 6502 CNRS-Université de Nantes, 2, rue de la Houssinière, BP 32229, 44322 Nantes Cedex 03, France Resume : The photoactive properties of titanium dioxide (TiO2) are very attractive allowing many applications in the environmental field (photocatalysis, super-hydrophilicity, photovoltaics…). In the latter domain, optimizing collection and transport of photogenerated charges requires the elaboration of a nanostructured and/or porous layer, therefore the surface/volume is increased. Most of these deposits are commonly elaborated by sol-gel process which requires an annealing step at high temperature (at least 450°C) for the crystallisation of TiO2. This technique has many disadvantages: decrease of the adherence to the substrate, partial destruction of the micro /nano-porosity and incompatibility with plastic substrates. We present a procedure for synthesizing TiO2 anatase nanocrystals (NCs) from the hydrolysis of the precursor [Ti8O12(H2O)24]Cl8.HCl.7H2O (denoted Ti8O12) in the presence of surfactants or not in soft solvothermal conditions (≤200°C). Particularly, it has been possible to obtain monodisperse anatase NCs with controlled shape. In addition, these NCs have been stabilized as colloidal solutions which allow us to carry out electrophoretic deposition (EPD). Finally, with this technique, we could deposit dense or porous nanostructured films of crystallized TiO2 at room temperature on various substrates. The NCs have been studied by TEM, XRD, Raman and IR spectroscopy and the deposits by SEM, EDX and XPS. | 2 7 |
| 14:00 | High Throughput Physical Vapour Deposition and Screening of Ferroelectric (Bi,Na)TiO3-BaTiO3 Thin Film Compounds Authors : Mark Darby, Samuel Guerin, Brian Hayden and Sergey Yakovlev Affiliations : Ilika Technologies Ltd., Kenneth Dibben House, University of Southampton Science Park, Chilworth, Southampton, SO16 7NS, United Kingdom Resume : Combinatorial synthesis has been recognized as an effective tool for accelerated discovery of new functional materials. Ilika has developed a series of high throughput workflows based on a proprietary high throughput materials synthesis method, High Throughput Physical Vapour Deposition (HT-PVD) for screening of inorganic thin-film compounds [1]. In this work, we demonstrate an efficiency and robustness of this approach for screening ferroelectric perovskites in the (Bi,Na)TiO3-BaTiO3 (BNT-BT) system. Polycrystalline thin film libraries of a wide composition spread in the BaO-TiO2-Na2O-Bi2O3 space with controlled composition gradients and thickness from 80 to 240 nm were deposited on platinized Si substrates from individual atom sources by HT-PVD; structural, dielectric and ferroelectric properties of the films were analysed. To our knowledge, this is the first report on the application of the PVD technique for synthesis of BNT-BT ferroelectric compounds. It was found that, in general, PVD processed BNT-BT thin films possess high relative permittivity (up to 350) and superior ferroelectric properties (compared to other deposition methods) with maximum remnant polarization Pr = 25 µC/cm2 in an appropriate composition range. Furthermore, employing HT-PVD technique allowed us to establish compositional boundaries of an existence of the ferroelectric perovskite phase. [1] S. Guerin, B.E. Hayden, J. Comb. Chem. 8 (2006) 66-73. | 2 8 |
| 14:15 | 2D Assembling of Iron Oxide Nanoparticles with Tunable Magnetic Properties Controlled by Click Chemistry Authors : D. Toulemon,1 B. P. Pichon,1 X. Cattoën,2 S. Bégin-Colin1 Affiliations : 1Institut de Physique et Chimie des Matériaux de Strasbourg, UMR CNRS-UdS 7504, Strasbourg, France. 2Institut Charles Gerhardt Montpellier ICG UMR 5253 ENSCM, Laboratoire AM2N 8 rue de l’Ecole Normale, 34296 Montpellier Cedex 5, France Resume : Magnetic nanoparticles (NPs) assemblies have attracted a huge attention due to their potential applications such as recording media or nanosensors. Because the magnetic collective properties of such nanostructures are strongly dependent on the spatial arrangement of NPs, self-assembly methods have been widely studied. Recently, 2D molecular nanopatterns consisting in self-assembled monolayers (SAMs) of organic molecules were shown to address the assembling of iron oxide NPs in sizeable domains through specific interactions. Although these methods produce well-defined nanostructures, NPs are usually assembled through weak interactions with the surface and may rearange as a result of interparticle interactions. Hence controlling the interparticle distance in 2D assemblies is not a trivial issue and requires new approaches allowing the stable anchoring of NPs on substrates.
While click chemistry has been widely investigated to functionalize NPs for bio-related applications through covalent linkage, it has been rarely reported to assemble NPs. Here we report on 2D magnetic iron oxide NPs assemblies prepared by combining SAMs and click chemistry (Toulemon et al, Chem. Comm. 2011, 47, 11954) i.e. by creating covalent triazole linkage between azide terminated NPs and an alkyne-terminated SAM. The dependent magnetic properties of these assemblies were studied as a function of the interparticle distance which was controlled by the kinetics of the reaction. | 2 9 |
| 14:30 | Electrospun nanoscale glass fibres Authors : M. Praeger (1), E. Saleh (1), A. Vaughan (2), W. J. Stewart (1), W. H. Loh (1) Affiliations : (1) Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ, United Kingdom; (2) Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ, United Kingdom; Resume : We report on the first successful demonstration of electrospinning of glass nanofibres directly from a non-polymer (boron trioxide) melt. The glass nanofibres are ~100 nm in diameter and hundreds of microns long. The single-step process eliminates any post-processing that is required when glass is spun from a sol-gel.
We also find that smaller gap distances between the tip containing the melt and the substrate help facilitate electrospinning for materials with higher surface tensions. Surface tension opposes the formation of the electro-hydrodynamic jet that drives the electrospinning process. Electrospinning of high surface tension materials in open atmosphere is usually frustrated by the onset of the electrical breakdown of air, which can cause tip and substrate damage and prevent the continuous application of a sufficiently intense electric field. In our work, it was found that the use of tip-to-substrate separations < 10 µm allowed electrospinning of the boron trioxide melt, in air, without electrical discharge.
The results indicate that a wide range of materials, and not just polymers, should be directly accessible to electrospinning - for the creation of a variety of nanofibres able to suit many novel applications. | 2 10 |
| 14:45 | Chalcogenide nanocrystals synthesis and films preparation for low-cost applications. Authors : A. de Kergommeaux (a,b), A. Fiore (a), J. Faure-Vincent (a), F. Chandezon (a), A. Pron (a), R. de Bettignies (b), and P. Reiss (a) Affiliations : (a) DSM/INAC/SPrAM (UMR 5819 CEA-CNRS-UJF), Laboratoire d’Electronique Moléculaire, Organique et Hybride, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble cedex 9, France. E-mail: antoine.deker@cea.fr (b) INES, CEA-DRT/LITEN/DTS/LMPV, Institut National de l’Energie Solaire, Le Bourget du Lac, FRANCE Resume : Owing to their size-dependent optical and electronic properties and solution processibility, colloidal semiconductor nanocrystals (NCs) have a high potential for various applications like solar cells, photodetectors and field effect transistors. Tin chalcogenide (SnS, Se, Te) and copper indium selenide (CISe) are of particular interest due to their low band gap and environmental benign character. Obtaining continuous and highly conductive NCs thin films presents one of the present key challenges for their use in (opto-) electronic devices.
We synthesized SnS and CISe NCs of 5-20 nm diameters, capped with insulating surface ligands (e.g. oleic acid, oleylamine). The NCs were deposited on ITO substrates using different techniques (spin coating, dip coating, Doctor Blade). We investigated the influence of pre- or post-deposition surface ligand exchange with small, crosslinking molecules on the morphology and transport properties. Depending on the deposition technique and nature of the ligands, smooth and compact films have been obtained as revealed by SEM and AFM. The measured current densities increased, as compared to the pristine NCs, by two orders of magnitude to values reaching mA.cm-2 at 1V for ethanedithiol-treated films of CuInSe2 NCs. Even higher conductivity has been achieved using molecular chalcogenide complex (MCC) ligands of Sn2S6(4-) type. A prototype solar cell without interface and electrodes optimization shows a clear photovoltaic effect. | 2 11 |
| 15:00 | New nanomaterial processes and fabrication methods for emerging low cost devices Authors : J.R. Morante Affiliations : Catalonia Institute for Energy Research, IREC, Jardins de les Dones de Negre 1, 08930 Sant Adrià de Besòs, Barcelona, Spain Department of Electronics, University of Barcelona, UB, Martí i Franquès 1, 08028 Barcelona, Spain Resume : Bottom up control of material properties are required to build the next generation of devices, sensors and micro&nanosystems. Nevertheless, at the nano level, shape and size determine structural and functional properties; surface/bulk ratio and surface characteristics define the transduction mechanisms involving photons, phonons, electrons and chemical which are basic for fix the multi-functional device properties; and effective doping becomes an outstanding basic parameter having strong influence on the final device behavior. Furthermore, higher level of miniaturization and lower power consumption claim too for having controlled building blocks compatible with advanced manufacturing technologies and fully autonomous systems.
In this scenario nanowires and nanoparticles constitute a very promising application, for sensing and as active elements and energy conversion cells. However, for their generalized and extended use all the above characteristics (shape, size,doping and surface state) must be controlled and understood at the nano level for achieving the right application of these properties as well as for obtaining the associated feasibility of the low cost processing nanotechnologies. Nevertheless, all of these items are still open features or not yet closed questions.
In this contribution, different experimental low cost approaches for controlling doping, size, and shape will be presented and discussed as well as the use of core/shell structures. | 2 12 |
| 15:30 | Coffee break | |
| 16:00 | Growth and Functional Properties of Rough ZnO Nanowires Authors : V. Galstyan, E. Comini, C. Baratto, M. Brisotto, E. Bontempi, G. Faglia, G. Sberveglieri Affiliations : V. Galstyan; E. Comini; C. Baratto; G. Faglia; G. Sberveglieri, SENSOR Lab, Department of Chemistry and Physics, Brescia University and CNR-IDASC, Via Valotti 9, 25133 Brescia, Italy. M. Brisotto; E. Bontempi, INSTM and Chemistry for Technologies Laboratory, Brescia University, Via Branze 28, 25133 Brescia, Italy. Resume : Many fabrication techniques have been applied for the production of ZnO nanostructures in a wide range of morphologies in order to improve the properties of the structures. This work reports fabrication of ZnO nanowires and investigation of their functional properties. ZnO nanowire arrays of high density and homogeneity were obtained by electrochemical anodization method. Anodization was carried out in a two-electrode system at room temperature by potentiostatic mode. Nanowires were prepared on stiff and flexible substrates such as alumina, silicon, glass and flexible polymeric substrates Kapton HN. The morphological investigations of the nanowire arrays showed that their surface is rough. The diameter of nanowires can be tuned by tailoring the anodization parameters in the range from the 20 to 110 nm, and more than 1 µm in length. The obtained structures were annealed at 400°C under the O2 atmosphere. The X-ray diffraction analysis showed that the structures were crystallized. Photoluminescence properties were also investigated. The samples showed typical ZnO spectrum with a small excitonic peak at 381 nm and a broad asymmetric band in the visible range, ascribed in literature to surface defects. The chemical sensing characteristics of the structures have been tested towards ethanol, acetone, carbon monoxide and nitrogen dioxide. The sensor response is quite high and the recovery of the signal is almost complete.
These preliminary results show that ZnO nanowires are interesting structure for chemical sensing, the low temperature process allow preparation on many types of substrates, even flexible ones. The prepared nanostructures also could have novel applications in optoelectronics and biomedical science because it is bio-safe. | 3 13 |
| 16:15 | Easy chemical –free alignment and integration of nanowires on device platform at room temperature Authors : Jihye Lee, Won Seok Lee, In-Kyu Park, Jeunghee Park Affiliations : Jihye Lee(Korea Institute of Machineray and Materials); Won Seok Lee, In-Kyu Park(KAIST);Jeunghee Park(Korea University) Resume : Recently there have been efforts to develop bottom-up fabrication of one-dimensional (1-D) nanostructures such as semiconductor nanowires and carbon nanotubes and to apply them to field effect transistors, light emitting devices, bio-sensors and flexible devices. In order to make advances in industrialization of these 1-D nanostructures-based devices, integration of 1-D nanostructures needs to be improved for their easy alignment, room temperature integration and chemical-free process.
In this paper, we demonstrate easy and chemical-free alignment and integration of nanowires into device platform at room temperature. Randomly grown ZnO nanowires were transferred onto intermediate substrate as aligned in one direction using dry transfer printing. Nanowires on the intermediate substrate were embedded into Au metal pads in device platform at room temperature using chemical-free compressive bonding method. Electrical characteristic of fabricated nanowire-based device showed Schottky contact of nanowires with Au metal. Additional thermal treatment could change the contact mode. The feasibility of the device as a UV sensor was demonstrated. This approach provides a large area integration of nanowires at room temperature and can be applied to flexible devices with enhanced reliability. | 3 14 |
| 16:30 | The alteration of functional properties in low dimensional ZnO nanostructures by shape anisotropy, size effects and metastable polymorphs Authors : M. R. Wagner1, J. S. Reparaz1, A. Hoffmann1, C. Lizandara-Pueyo2, S. Siroky2, S. Landsmann2, S. Polarz2 Affiliations : 1 Institute of Solid State Physics, Technical University Berlin, 10623 Berlin, Germany; 2 Department for Chemistry, University of Konstanz, 78457 Konstanz, Germany Resume : The morphology (shape, size, lattice structure) of materials is a central parameter influencing its functional properties. At the nanoscale, it is expected that a change in morphology implies a measurable alteration of the material properties. In this work, we present recent advances in the modification of these properties in ZnO based nanostructures. The influence of a shape modification is demonstrated by a new non-equilibrium shape of trigonal prismatic ZnO nanoparticles with adjustable aspect ratios which were synthesized from organo-metallic precursors. As most prominent effect it is observed that the shortening of the nanoprisms induces a decrease of the bandgap up to 200meV contrary to the quantum size effect. Important changes in properties are also observed in many instances when materials possessing different crystal structure are considered. The formation of a new, nano crystaline ZnO phase with 99% purity is also reported. The analysis of this phase with a variety of analytical methods including x-ray diffraction, high-resolution TEM, micro-Raman and micro-PL leads to the conclusion that a metastable ZnO with a crystal structure resembling the alpha-boron nitride structure has been prepared. Finally, significant finite-size effects are observed in ZnO nanowires with varying length and diameter effecting the exciton lifetime as demonstrated by time resolved photoluminescence studies. The results can be explained considering the influence of surface defects and optical modes in the nanowires. In conclusion, the preparation and investigation of different ZnO morphologies on the nanoscale impressively demonstrates the huge potential of alternated functional properties for novel applications. | 3 15 |
| 16:45 | Metal-assisted etching of Silicon nanowires: Fabrication methods and understanding of the etching mechanism Authors : Nadine Geyer, Bodo Fuhrmann, Hartmut S. Leipner, Alexander Tonkikh, Peter Werner Affiliations : Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle; Interdisciplinary Center of Materials Science, Martin-Luther-University Halle Wittenberg, Heinrich-Damerow-Straße 4, D-06120 Halle Resume : Silicon nanowires (SiNWs) are attractive structures for potential applications in optoelectronics and appear promising for thermoelectric devices and sensors. In recent years, a simple metal-assisted etching method, using noble metal films as a catalyst, has been developed for the controlled fabrication of vertically aligned SiNWs or Si/Ge superlattice nanowires on Si wafers. The working principle of metal-assisted etching is based on a local oxidation and dissolution of Si in HF in presence of an oxidizing agent. Here, the noble metal layer facilitates the etching process. This dissolution of the oxidized Si leads to a simultaneous pitting of the noble metal film into the resulting pores in the Si substrate. Applying metal-assisted etching for the fabrication of SiNWs, NWs with diameters in the range of several µm down to 10 nm can be achieved. High area densities of 10^10 wires/cm², as well as the control of diameter, length and position of the wires are possible. Whereas the etching of SiNWs is successfully applied, the etching mechanism of the nanowire formation is still not well understood on a microscopic scale. The aim of this work is the investigation of etching phenomena like the etching rate and the morphology in dependence of several parameters. Based on the experimental results, a mechanism for the formation of SiNWs by metal-assisted etching is proposed. With the understanding of the etching mechanism the properties of the SiNWs can be tailored. | 3 16 |
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