Hall-thermopower sign anomaly in chalcogenide glasses

Abstract

Recent models for the electronic structure of multicomponent chalcogenide glasses have led to the conclusion that the Fermi level is essentially pinned near the center of the gap by a relatively low-energy defect center. Expressions for the conductivity, thermoelectric power, and Hall coefficient of these glasses are calculated within such a model. When the effective mass of holes in the valence band is larger than that of electrons in the conduction band, it is found that a $p$-type thermopower and an $n$-type Hall coefficient can coexist over a wide temperature range, an anomaly which has been reported for a variety of glasses. In addition, the model explains several salient features of the transport coefficients measured in some of these glasses.