AmorphousSixGe1−xO2. I. Electronic structure

The electronic structures of amorphous ${\mathrm{Si}}_x{\mathrm{Ge}}_{1-x}{\mathrm{O}}_2$ alloys are calculated for the entire range of concentrations and are found to be in good agreement with recent ultraviolet-photoemission data. The calculations are performed using a cluster-Bethe lattice structure including Si(Ge)-O-Si(Ge) bond-angle variation and keeping perfect $s{p}^3$ hybridization at the semiconductor atoms. The distribution of Si and Ge atoms in the alloy is found to be random with only Si(Ge)-O bonds. Inclusion of bond-angle variation is necessary to reproduce some of the experimentally found features.