Doping effect of copper in germanium tellurium semiconducting glass system

Addition of copper to the semiconducting glassy system Ge15Te85−xCux (x=2, 4, 5, 6, 8, and 10) at the tellurium site is seen to produce considerable changes in the glass transition temperature (Tg) of the system. For a particular value of copper percentage, the Tg shows a minimum critical value. We have made an attempt to explain the observed variation of Tg with Cu content on the basis of various models like the chemically ordered network model, the constraints theory, the covalent bond approach of Tichy and Ticha and former valence shell (FVS) model proposed by Liu and Taylor.