Significant field effects have been reported in chalcogenide glasses, despite the pinning of the Fermi energy by valence alternation pairs. It is shown that the existence of a potential barrier between the two neutral defect centers is responsible for this, but the field effect should decay away with time. It is predicted that the relaxation times are temperature activated, and the activation energies can be used to determine the density of localized states in the gap. New experimental data are reported which demonstrate all of these effects.

• Received 1 December 1980

DOI:https://doi.org/10.1103/PhysRevLett.46.1027