Density of states of a-Si1−yNiy:H alloys determined by X-ray and optical spectroscopies

Abstract

The density of valence states of amorphous hydrogenated silicon-nickel a-Si1−yNiy:H alloys has been experimentally investigated by soft X-ray emission (SXS) and optical spectroscopies. By SXS, partial Si 3p and Ni 3d valence states are obtained on a common energy scale referred to the Fermi level. Our results show that, as the Ni content is increased, the uppermost valence band changes from Si 3p to hybridized Si 3p-Ni 3d states, leading to a finite density of states at the Fermi level. The results are discussed in relation to optical measurements performed on samples deposited at the same time.