Impurity states in amorphous As2Te3

Abstract Amorphous films of (As2Te3)1–x M x where M = Mn, Ni, Cu, Ge, Pt and Pb were deposited at 77 K. Hopping conductivity and localized paramagnetic defect states, evidenced by an E.S.R. signal with a 16 G linewidth at g = 2, were observed in all as-deposited films. The defect states disappeared upon annealing, and in the case of Mn the impurity states (wide E.S.R. lines at g = 2 and g = 4·3) are then observed. Although theoretically the same behaviour is expected with Ni, Cu and Pt no impurity state could be detected by E.S.R. In order to understand this inconsistency and the contradictory results of apparently similar experiments in different laboratories, we combined the results of resistivity and E.S.R. measurements with those obtained by transmission electron microscopy. The conclusion is that most experiments can be obscured by clustering of the impurity: in glasses because of low solubility limits and high atomic mobility and in films because of the low-density network present in all amorphous s...