Impurity scattering of a two-dimensional gas calculated in the charge-sheet approximation

Abstract

A simplified form of the screened impurity potential is used in the calculation of the impurity-scattering limited mobility. The simplification is based on modeling the two-dimensional gas as a charge sheet removed from the interface by some distance. It is shown that for the practical values of electron concentrations (1011–1012 cm−2), a good agreement with the exactly calculated mobility can be reached if one takes this distance equal to 0.55zav, where zav is the average separation of the two-dimensional electrons from the interface. The relative error does not exceed 20% in the case of scattering by the interface impurity centers and 10% in the case of the scattering by the remote centers. In the latter case the error decreases with the increased thickness of an undoped spacer layer. The proposed sheet model of the two-dimensional gas can be used in numerical calculations of the impurity scattering effects where accuracy of the calculated mobility plays a secondary role.