Short-range order in Se-rich Ge-Se glasses - An extended X-ray absorption fine structure study

The short-range order in vitreous Ge1-xSex (2/3 less than or equal to x less than or equal to 1) at 80 K was studied by EXAFS spectroscopy at the Ge and Se K-edges. The results were analyzed using theoretical. phase shift and amplitude functions and by comparison to crystalline GeSe2 and Se as model compounds. The GeSe4 tetrahedron is the main structural entity for all the Ge-Se alloys, The results indicate a slight increase in Ge coordination and a decrease in Se coordination with increasing Se content, Possible sources of error are discussed, and possible origins of the structural changes are suggested. (C) 1999 Academic Press.