LOCALIZED-STATE DISTRIBUTIONS IN AG-MODIFIED AS2SE3 GLASSES

Localized-state distributions in Ag,(As0.4Se0.6)(100-x) glasses, where 0 less than or equal to x less than or equal to 35, have been investigated using the transient photoconductivity technique. In all the glasses, the density of tail states above the valence band appears to be distributed exponentially, proportional to exp(-E/kT(0)), where T-0 is the characteristic temperature. With an increase in x, T-0 increases, but at x greater than or equal to 10, it decreases. This composition dependence can be accounted for by assuming the formation of Ag-Se bonding states above the nonbonding Se valence band.