Formation of cubic SiC nanocrystals by laser-assisted CVD

Abstract

Nanocrystals of cubic silicon carbide (SiC) are formed using laser-assisted chemical vapor deposition. A CO 2 laser beam is mechanically chopped to obtain pulsed infra-red excitation. Silane (SiH 4 ) and acetylene (C 2 H 2 ) have been used as precursors. The formed SiC has the zinc-blende crystal phase (β-phase) with an average primary particle size of about 12 nm. As expected, higher chop frequencies yield smaller crystals. To establish electronic isolation between the particles, a native oxide shell of SiO 2 can be formed by heating the particles in air. Subsequent etching with HF removes the oxide shell leading to further reduction of the particle size down to 4 nm.