Incorporation of Ga into the structure of Ge–Se glasses

The structure of Ga-containing Ge–Se glasses is studied by high-resolution X-ray photoelectron and extended X-ray absorption fine-structure spectroscopies. The results show that in GaxGeySe100–x–y glasses both Ga and Ge atoms are 4-fold coordinated, whereas Se atoms are 2-fold coordinated. For Se-deficit samples with Se content less than 67 at.%, Ge–Ge(Ga) bonds appear. First, Ge–Ge bonds are formed indicating preference for the formation of (Se)2 > Ga < (Se)2 units over the regular GeSe4/2 tetrahedra. Metal-Ga bonds appear only in the most Se-deficit sample. Addition of Ga facilitates more uniform Se distribution in comparison to binary Ge–Se or ternary As(Sb)–Ge–Se systems. The observed structural features are correlated with some basic thermo-mechanical properties of the investigated glasses.

► Structural and electronic properties of Ga–Ge–Se glasses are studied by XPS and EXAFS. ► Nearest surroundings for each constituting element are identified and quantified. ► Average local coordination of Ga, Ge and Se are determined to be 4, 4 and 2, respectively.