We measured the effect of alloy composition on the atomic bonding in bulk ${\mathrm{Ge}}_{1-x}{\mathrm{Si}}_x$ alloys grown by the Czochralski method across the whole composition range $0<x<\mathrm{}1.\mathrm{}$ Extended x-ray-absorption fine-structure measurements performed at the Ge K edge at 20 K found that the Ge-Ge and Ge-Si bond lengths maintain distinctly different lengths and vary linearly with alloy composition. The topological rigidity parameter, estimated from the measured bond lengths, is around 0.6, which indicates that the bond lengths and bond angles are distorted with alloy composition.

• Received 26 March 2001

DOI:https://doi.org/10.1103/PhysRevB.64.113206