FACTORS DETERMINING THE COMPOSITION OF STRAINED GESI LAYERS GROWN WITH DISILANE AND GERMANE

Growth rates and compositions are reported for GeSi alloy films and su perlattices epitaxially grown on both Ge(100) and Si(100) substrates u sing disilane and germane source gases in an ultrahigh vacuum chemical vapor deposition chamber. Although the growth rate changes rapidly wi th temperature the composition is nearly independent of it. Specifical ly, we find that the order of the adsorption reaction for disilane and germane is the same, resulting in the composition being determined by the partial pressures and by the ratio of the adsorption reaction rat e constants. This ratio depends very weakly on temperature, if at all, and appears to vary slightly with the layer composition. (C) 1994 Ame rican Institute of Physics.