Influence of donor-donor interaction on the metal-insulator transition in doped semiconductors

The Molt metal-insulator transition in slightly compensated semiconductors with a simple dispersion law (of the InSb type) is investigated. A microscopic description is given for the metal-insulator transition under conditions such that the impurity band overlaps the conduction band in the vicinity of the transition point, and the Fermai level lies in the conduction band. Based on the condition of minimum internal energy of the system of electrons and donors it is shown that allowing for donor-donor interaction reads to stabilization of the intermediate state, in which donors are partially ionized, Ie is shown that, in a certain interval of near-critical donor densities, the magnetic field induces a transition from the insulator to the metallic phase by suppressing the van der Waals forces of interaction of neutral donors. A parallel is drawn with analogous phenomena associated with weak localization effects in highly compensated semiconductors (Anderson transition). (C) 1997 American Institute of Physics.