Ionized impurity scattering in semiconductors

Abstract

Abstract In the Brooks‐Herring‐formula the scattering centres are assumed to be independent. The range of validity of this assumption is investigated. For this purpose the scattering of electrons by a pair of impurities is considered as a function of its internal separation and its orientation with respect to the electronic current. For a separation larger than about the Debye‐Hückel screening length the ionized impurities are found to act as independent scattering centres. For smaller separations the interaction of the scattering centres cannot be neglected.