Nanoscale Heterogeneities in Amorphous Semiconductorxmetal1–x Alloys: A Small-angle X-ray Scattering Study

Abstract

A series of small-angle x-ray scattering (SAXS) experiments has been conducted in order to probe further the X-ray absorption fine structure (EXAFS)-derived nanoscale structure of amorphous hydrogenated siliconxtin1–x, hydrogenated siliconxnickel1x, and germaniumxgold1–x materials as a function of metal content. The SAXS results reveal information on cluster formation within these reactively radio-frequency–sputtered amorphous thin films. The data are considered within the context of EXAFS data and lend support to a model in which the degree and nature of the heterogeneities depend primarily on the metal species, with the level of metal content inducing additional effects. In particular, the results support a percolation model for the metal: nonmetal transition in amorphous semiconductorxtransition metal1–x alloys, the conducting volume elements comprising metal or metal compound-rich regions within the amorphous tetrahedral host network.