Atomic arrangement in the glassy semiconductor Ge30As20Se50

Abstract Two tridimensional models of Ge 30 As 20 Se 50 amorphous alloy have been built by theoretical simulation of the experimental Radial Distribution Function (RDF) calculated from the X-ray diffraction data of a powder sample of the studied alloy. The models are discussed from topological and geometric point of view and an analysis of the main structural parameters is carried out in order to proposed a real average structure of the material. Both models fit the experimental RDF and abide by the geometrical conditions. But a model formed by clusters of tetrahedra with some overlapping linked to each other by As and Se chains has been considered more probable from topological considerations. This model has a better agreement with the shortrange order supposed from the RDF preliminary analysis, glass transition temperature and electronic structure.