The Cu and Te coordination environments in Cu-doped Ge–Te glasses

Abstract

The structure of Ge 20Te 80, Ge 15Cu 8Te 77 and Ge 15Cu 5Te 80 glasses was investigated by diffraction techniques and extended X-ray absorption fine structure measurements. Large structural models were generated by fitting experimental data by the reverse Monte Carlo simulation technique. In Ge 20Te 80 glass, both Ge and Te obey the 8 − N rule, and the structure is built up of GeTe 4 tetrahedra connected via Te–Te bonding or shared Te atoms connected to two Ge atoms. The coordination number of Te is significantly higher than 2 in Ge 15Cu 8Te 77. The average coordination number of Cu is 3.41 ± 1 in this alloy. In Ge 15Cu 5Te 80 glass, Cu binds mostly to Te, while Cu–Cu bonding is significant in Ge 15Cu 8Te 77.