Effects of disorder on electronic structures of a-Si:H and a-${\mathrm{SiO}}_2$

Si $L_{23}$ x-ray emission spectra from c-Si, doped and intrinsic a-Si:H, quartz, and a-${\mathrm{SiO}}_2$ are presented. The first and second moments of the valence-band transition density of states of each of these samples were computed. The variance of the disorder potential that characterizes the amorphous network was found for the amorphous samples from their second moments. Lifetime broadening as a function of energy in the valence band of silicon samples was found to vary significantly between the crystalline and amorphous structures.