THERMAL-STABILITY OF SI SI1-X-YGEXCY/SI HETEROSTRUCTURES GROWN BY RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION/

High quality pseudomorphic Si1-x-yGexCy alloy layers were grown on (10 0) silicon substrates by rapid thermal chemical vapor deposition with 0 or 11 at% Ge and 0.5 or 1 at% C. The relaxation behavior of these st rained layers was investigated using rapid thermal annealing between 1 000 and 1130 degrees C. Substitutional C gradually precipitated out to form cubic silicon carbide (beta-SiC). The in-plane lattice constant remained constant after annealing, indicating that there was no mechan ical strain relaxation by misfit dislocations. The perpendicular latti ce constant increased due to the decreasing substitutional C concentra tion. The same behavior was observed for both SiC and SiGeC samples, s howing that Ge did not influence C precipitation. C atoms diffused ove r very short distances before they precipitated. It appears that, once formed, the beta-SiC particles stayed put. Germanium out-diffusion wa s found to be somewhat higher than calculated with published diffusion coefficients.