KINETICS OF THE LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION OF POLYCRYSTALLINE GERMANIUM-SILICON ALLOYS FROM SIH4 AND GEH4

A Langmuir-Hinshelwood growth-rate equation is presented for the germanium-silicon (GeSi) alloy deposition from GeH4 and SiH4 assuming dissociative chemisorption on a heterogeneous GeSi surface. Model parameters for the deposition kinetics have been extracted from measurements. The fit for the bond-energy of hydrogen to a germanium surface site is 30 kJ mol-1, lower compared to that of hydrogen to a silicon site. We found to a good approximation the GeSi composition of the alloy to be independent of the temperature. Moreover, the GeSi is polycrystalline down to the lowest deposition temperature we used, ie., 450-degrees-C.