Formation of cubic SiC nanocrystals by laser-assisted CVD

摘要

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_2H_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.