Nanoscale heterogeneities in amorphous semiconductor(x)metal(1-x) alloys: A small-angle x-ray scattering study

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 silicon(x)tin(1-x), hydrogenated silicon(x)nickell(1-x), and germanium,gold(1-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 semiconductor,transition metal(1-x), alloys, the conducting volume elements comprising metal or metal compound-rich regions within the amorphous tetrahedral host network.