X-ray photoelectron spectra of Ge-As-Te glasses

Ternary Ge10AsxTe90-x glasses with a mean coordination number (MCN) from 2.3 to 2.8 were prepared, and their physical and structural properties were characterized. It was found that, the density of the glass decreases but glass transition temperature Tg increases, and the near infrared transmission edge shifts to shorter wavelength with increasing As content. The Ge, As, and Te 3d spectra were decomposed into different doublets that correspond to different structural units and the results showed that, the numbers of Te-Te-Te trimmers and Te-Te-As(Ge) structural units decrease and finally disappear, while the perfect AsTe3/2 pyramidal and GeTe4/2 tetrahedral structure in Te-rich samples gradually transferred to defect structures including As-As and Ge-Ge homopolar bonds with increasing As concentration. No threshold behaviour can be found in the structural evolution of Ge10AsxTe90-x glasses due to a large atomic contrast between As and Te, and no any change in the chemical coordination of Te can be observed even in Te-poor glasses.