Extended x-ray absorption fine-structure study of hydrogenated amorphous silicon-germanium alloys

The local structure of hydrogenated amorphous Ge-Si alloys has been studied by measuring the x-ray absorption at the Ge K edge. Ge-Ge and Ge-Si distances were found to be independent of concentration and equal to 2.45 and 2.38 {}, respectively. A study of the composition of the first coordination shell around Ge is consistent with a random mixing of the two species in the alloys. The total disorder factors have been determined for both Ge-Ge and Ge-Si, and they turned out to be constant and equal to each other over the whole concentration range studied.