New model for one-electron gap states in amorphous germanium

In order to explain the dc electrical conductivity in amorphous germanium, a new model for the one-electron states in the gap is proposed. It is based on the notion of strong interaction between a carrier and the lattice. The model explains a number of experimental observations apart from the dc electrical conductivity, notably the thermopower and induced optical absorption. It also leads to some predictions about the dielectric response at low frequencies (ac conductivity below ${10}^9$ Hz). The proposed model leads naturally to the concept of diamagnetic, doubly occupied, localized states for strong enough coupling of the carrier to the lattice and predicts disappearance of mobility edges from one-particle energy spectrum in the study of electrical transport phenomena.