Alloy scattering ofn-type carriers inGaNxAs1−x

Abstract

A tight-binding model of the electronic structure of substitutional nitrogen in GaAs, together with a variational description of quasilocalized nitrogen-induced electronic states near the conduction band edge, is used to calculate the nitrogen-related alloy scattering of conduction band electrons in the dilute nitride alloy, $\mathrm{Ga}{\mathrm{N}}_{x}{\mathrm{As}}_{1\ensuremath{-}x}$. The electron mobility in the nondegenerate and degenerate doping regimes is calculated for bulk and quantum well geometries from the energy-dependent scattering rate using the Boltzmann transport equation in the relaxation-time approximation. Nitrogen cluster states are found to dominate the scattering near the conduction band edge and play a crucial role in limiting the electron mobility. In the experimentally relevant regime of degenerate doping and at nitrogen concentrations of 1 to 2%, the room-temperature mobility is found to be limited to values less than $300\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}{(\mathrm{V}\phantom{\rule{0.2em}{0ex}}\mathrm{s})}^{\ensuremath{-}1}$, in agreement with experimental measurements.