Quantitative ASAXS of germanium inhomogeneities in amorphous silicon–germanium alloys

The nanostructure of hydrogenated amorphous silicon germanium alloys, a-Si1−xGex:H (x ∼ 0.15 to 0.57), prepared by different plasma enhanced chemical vapor deposition (PECVD) techniques was analyzed by anomalous small-angle X-ray scattering (ASAXS) experiments. For alloys with x>0.2 the Ge component was found to be inhomogeneously distributed with correlation lengths from 0.6 to 1.6 nm. From the analysis of extended ASAXS measurements at 16 X-ray energies in combination with densitometric measurements the volume fractions, densities and Ge-concentrations of the inhomogeneities were deduced.