Local structure of bulk amorphous and crystalline (GaSb)(1-x)(Ge-2)(x)

The local structure of bulk amorphous and crystalline (GaSb)(1-x)(Ge-2)(x), produced by solid-state amorphization and subsequent crystallization of am orphous samples, respectively,have been studied using extended x-ray absorp tion fine-structure. Measurements have been made alt the Ga and Ge K edges for c-(GaSb)(1-x)Ge-x, and at all K absorption edges for a-(GaSb)(1-x)Ge-x. All samples are found to be fourfold coordinated with a local structure cl ose to the c-GaSb or the c-Ge phase. The partial distances RGa-Sb,RGe-Sb ,R Ge-Ga ,RGa-Ge ,RSb-Ga and Rsb-Ge are shown to be independent of Ge concentr ation and defined by covalent radii of the components in both materials. Th e nature of local ordering in the amorphous materials is such that Ge seems to substitute mainly for Sb at lower Ge concentration (x < 30-40 at. %), a iding relief of stress inserted during amorphization of the material. Cryst alline (GaSb)(1-x)(Ge-2)(x) seems to contain a phase with around 4 Ga/Ge ne ighbors around Ge along with Ge randomly substituting on Ga and Sb sites in a solid solution. Debye-Waller broadening of amorphous and crystalline a-( GaSb)(1-x)Ge-x are of the same order of magnitude, suggesting chemical diso rder in the crystalline material.