Comparison of the structure of amorphous Ge and GaAs

The radial distribution functions of amorphous Ge and GaAs have been determined by X-ray diffraction with sufficient accuracy to reliably establish, for the first time, differences in the two structures. The staggered configuration is found to be favored in both structures, but much more so in amorphous GaAs than in amorphous Ge. This result is interpreted, using structural models, as also implying a difference in ring statistics, with a negligible fraction of 5-membered rings in amorphous GaAs.