Crystalline-to-amorphous transition in chemical vapor deposition of pseudomorphic Si1-x-yGexCy films

Pseudomorphic SiGeC films have been grown on (100) Si by atmospheric pressure chemical vapor deposition at 600 and 700 degrees C using SiH2Cl2, GeH4, and C2H4 precursors. Films with C concentrations of up to 2.5 at. % were entirely pseudomorphic and a 120-nm-thick Si66.5Ge31C2.5 film had 90% substitutional carbon. With increasing C incorporation due to increased ethylene flow, a layered structure was formed consisting of an amorphous film overlaying a buried pseudomorphic film. The crystalline-to-amorphous transition was initiated by the accumulation of C on the epitaxial growth surface. This deteriorated surface resulted in the formation of stacking faults along {111} planes and subsequent amorphization. Defect formation and amorphization could be prevented by periodically growing a thin Si epilayer. (C) 1997 American Institute of Physics.