Study of Ga incorporation in glassy arsenic selenides by high-resolution XPS and EXAFS

Effect of Ga addition on the structure of vitreous As₂Se₃ is studied using high-resolution X-ray photoelectron spectroscopy and extended X-ray absorption fine structure techniques. The “8-N” rule is shown to be violated for Ga atoms and, possibly, for certain number of As atoms. On the contrary, Se keeps its 2-fold coordination according to “8-N” rule in the amorphous phase throughout all the compositions. Crystalline inclusions appear in the amorphous structure of the investigated glasses at Ga concentrations greater than 3 at. %. These inclusions are presumably associated with Ga₂Se₃ crystallites and transition phases/defects formed at the boundaries of these crystallites and host amorphous matrix. The existence of Ga–As and Se–Se bonds in the samples with higher Ga content is supported by present studies