PUMA
Istituto dei materiali per l'elettronica ed il magnetismo     
Attolini G., Bosi M., Rossi F., Watts B. E., Salviati G. Cubic Silicon Carbide: a promising material for automotive application. In: NANOTEC - Venezia NANOTEC 2008 - Convegno Internazionale sulle Nanotecnologie (Venezia, 10-13 marzo 2008).
 
 
Abstract
(English)
carbide is a material that possesses properties that make it desirable in electronic, structural and sensor applications. As a wide band gap semiconductor it can be used in high power, high temperature electronics and harsh environments. Its hardness, wear resistance, chemical inertness, and thermal conductivity find uses ranging from disc brakes to micron scale sensors and actuators. The automotive industry faces some important challenges since it has obligations to manufacture safe, clean, energy efficient vehicles, which will be achieved by incorporating new technology. SiC based electronic and mechanical microsystems and nanoscale devices have advantages such as high operating temperatures eg. piezoelectric sensors could operate up to 1000 C. These can be used to control cylinder pressure, combustion temperature, combustion flame speed, engine output torque, wheel forces and chassis, road forces on wheel, suspension forces and torques. Although the manufacturing price of SiC is high the total cost of ownership could be offset by its robustness and high performance. In addition, developments in SiC growth in the heteroepitaxial growth on cheap Si substrates and new nanostructures, notably, nanowires (NWs) will spread this material into mass markets. The technology developed at IMEM/CNR for the preparation of SiC on 2 Si substrates and the growth of SiC nanowires is presented. - 3C-SiC layers are deposited on 2 Si wafers by means of Vapour Phase Epitaxy. The growth is performed in a home made reactor with induction heating. Gaseous (SiH4 and C3H8) and solid/liquid (CBr4 from a bubbler) precursors are used. A growth procedure involves several steps (thermal etching, carburisation, epi-growth) and the type of film can be varied depending on the processing. Samples analysis to find determine film morphology, composition and structure is performed by X-ray diffraction Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The film can then be micromachined to realise cantilevers and diaphragms employed in accelerometers, high-resolution strain gauges, diaphram pressure sensors, Micro Electro Mechanical System (MEMS). - SiC nanowires are prepared with carbon monoxide and nickel as the catalyst, in nitrogen or argon atmospheres at temperatures between 1050 and 1100C in a open tube reaction. This method is based on the carbothermal reduction of silica that takes place on the native oxide a silicon substrate surface. X-ray diffraction indicates that the films are of good crystalline perfection. Scanning Electron Microscopy studies of the nanowires show that wires have diameter less than 80 nm and are several tens of microns long. Transmission Electron Microscope images and diffraction patterns indicate that the wires grow along <111> axes and are monocrystalline. These results will be presented. SiC nanowires can be incorporated into gas sensors having high sensitivity, fast response time, lower power requirement than conventional sensors; this, due to high surface area to volume ratio. Single crystal, untwinned SiC fibres with <111> orientation may be useful as a piezoelectric in microsystems.
Subject Silicon Carbide nanowires
Thin Film
MEMS


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