Impurity States in n-Type Many-Valley Semiconductors

摘要

A self-consistent unrestricted Hartree Fock Roothan cluster calculation that takes into account the many valley effects of the host conduction band was performed to investigate the microscopic structure of impurity bands in doped semiconductors. The measure of localization was carried out through the inverse participation ratio (IPR). While the lower and the upper Hubbard bands are well defined at low concentrations, the donor excitonic states are important at higher concentration where the upper Hubbard band is pushed into the conduction band. The Mott Hubbard Anderson model thus modified can still explain almost all the experimental results. This cluster model allows numerical investigations of the thermodynamic, magnetic and transport properties.