Ideal-Real Semiconducting Glass and Low-High Conductivity Transition

Potential perturbations caused by about 10(20) cm(-3) of charged defects are characteristic for real glasses and cause a marked reduction of the mobility near the mobility edge as compared to ideal glasses. The conduction mechanism in real glasses is suggested to be carrier drift at a conductivity edge over barriers provided by Coulomb- repulsive defects. Evidence is given by analysis of numerous optical and electrical properties that the carrier mobility is of the order of 10(2) cm(2)/Vs in spite of a Hall mobility which is at least three orders of magnitude smaller. A simple change of the conduction mechanism, as the barriers are rendered ineffective at elevated temperatures, during the switching transition is suggested for explanation of the Ovshinsky effect.