Large scale epitaxial deposition reactors for production of high purity SiC for space devices
- Paper number
IAC-06-E2.1.01
- Author
Mr. Alessandro Fiorucci, Politecnico di Milano, Italy
- Year
2006
- Abstract
Silicon Carbide (SiC) is a very promising material for high power, high frequency and high temperature and electronic devices due to its unique properties such as large bandgap, high thermal conductivity, good corrosion resistance and other desirable characteristics. In particular, high specific stiffness and high thermal conductivity make Silicon Carbide important for space applications. The production process of Silicon Carbide depends on its applications: nowadays SiC is used mostly for mirrors in space based telescopes or structural supports. For this kind of devices, the used SiC is that got by sintering or by chemical vapour deposition (CVD). Nowadays, SiC is used mostly for telescopes, that need mirrors with a well defined curvature radius; for this genre of devices can be used sintered SiC. Sintering is a process by which powders are compressed in a die at a temperature minor to that of fusion for the material to mould it to the required shape, without using any adhesive material. This kind of process is extremely simple, and well developed, but, on the other hand, can be necessary to have a material with better performances: in this case CVD SiC is preferred. Chemical vapour deposition is a process by which, using a monocrystalline seed, can be obtained single-crystal high purity SiC. The study of the gas phase and adsorbed phase reactions is basilar for achieving a good product. In particular can be important to study the doping of SiC for the production of n-doped (usually with nitrogen) and p-doped (with aluminium) material: in fact the production of p-n SiC junctions is the future for electrical applications, especially for space applications, where the good properties of stiffness of silicon carbide can be very useful. The process is developed in large scale reactors, where epitaxial growth ( that means growth on a monocrystalline SiC seed ) is achieved by feeding gaseous reactants (usually SiH4, C3H8 diluted in a H2 stream, plus eventually N2 or Al(CH3)3 for having doping) that react in gas phase, reaching equilibrium conditions quickly, and with the superficial species (that are considered in first approximation of two kinds, adsorbed C and Si) to have growth of a monocrystalline solid. Through a modelling work, using sperimental data obtained by the pilot plant of the Epitaxial Technology Center in Contrada Torre Allegra, Catania (Italy), we studied how to minimize the non stoichiometric excess (modelled with SiC2 and Si2C molecules) and how to achieve good doping concentrations, in order to have an homogeneous material with good mechanical and electric properties.
- Abstract document
- Manuscript document
IAC-06-E2.1.01.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.