Low-temperature heteroepitaxial growth of SiGe on Si with low-pressure chemical vapor deposition

Abstract

SiGe heteroepitaxial layers were grown on (001)Si substrates by low-pressure CVD using Si 2H 6 and GeH 4. The relations between the growth rates, the Ge composition of epitaxial layers, and the growth conditions such as the partial pressure of source gas and the growth temperature were studied. It was found that the Ge deposition rate is a dominant factor controlling the Ge composition and growth rate of SiGe layers. Both Si and Ge component deposition rates are enhanced by Ge deposited on the growth surface. This suggests that the surface Ge atom acts as a catalyst for the decompositions of both Si 2H 6 and GeH 4. Nonlinearity observed in the dependence of the SiGe growth rate on the GeH 4 partial pressure can be explained by taking account of this catalysis. Activation energies in Si, SiGe and Ge depositions were estimated to be 1.7, 1.5, and 0.5 eV. For growth of SiGe, the activation energy almost never depends on the Ge composition. It was found that the deposition kinetics of the Ge atom in pure Ge growth differ greatly from those in the SiGe growth.