Conduction Processes in High Acceptor Concentration HgTe

Abstract

AbstractThe effects of vacancy induced acceptors in zero gap semiconductors, like in HgTe, are treated by the resonant state theory. First, one scattering center is considered, then multiple scattering is developed in the case of acceptor concentrations up to 1 × 1022 m−3. In this investigation the effects of even higher acceptor concentrations (N ≥ 1 × 1023 m−3) are elucidated. It is shown that in this case the resonant state model is no longer applicable since the randomly distributed impurities result in a fluctuating potential field. Thus the impurity disorder introduces an Anderson type conduction process. This is characterized by a large change in the mobility when the Fermi level goes through the acceptor band. These mobilities, related to the Anderson type conduction mechanisms, are in good agreement with the experimentally determined ones in the case of HgTe. While using the resonant state theory, the predicted mobilities are not in satisfactory agreement with the measured ones in the high acceptor concentration range analyzed in this investigation.