Formation of cubic SiC nanocrystals by laser-assisted CVD

Nanocrystals of cubic silicon carbide (SiC) are formed using laser-assisted chemical vapor deposition. A CO2 laser beam is mechanically chopped to obt ain pulsed infra-red excitation. Silane (SiH4) and acetylene (C2H2) have be en used as precursors. The formed SiC has the zinc-blende crystal phase (be ta -phase) with an average primary particle size of about 12 nrn. As expect ed, higher chop frequencies yield smaller crystals. To establish electronic isolation between the particles, a native oxide shell Of SiO2 can be forme d by heating the particles in air. Subsequent etching with HF removes the o xide shell leading to further reduction of the particle size down to 4 nm.