Analysis of short-range order and structural model in the glassy semiconductor Ge 0.20Sb 0.20Se 0.60 by X-ray diffraction

Abstract

An X-ray radial atomic distribution (RDF) study of the amorphous alloy Ge 0.20Sb 0.20Se 0.60 was performed. Short-range order information was obtained by interpreting the RDF data using a theoretical expression which takes into account the variation of the atomic scattering factors with s, the scattering vector modulus. The existence of tetra- and tri-coordinated germanium atoms, suggested in the literature for glassy alloys containing this element, was found to be compatible with the experimentally obtained structural information. A spatial distribution model was generated according to these two possible coordinations for germanium, using the conveniently modified Metropolis Monte Carlo method. The model exhibits tetrahedral units on germanium atoms, forming a network with triangular pyramids with a germanium atom at some vertices. A comparative analysis of the parameters of this model showed good agreement with the values given in the literature for similar alloys.