Intrinsic free carrier mobility of quantum wells in polar materials

Abstract

The intrinsic mobility of $\mathrm{Al}\mathrm{Ga}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ quantum wells is numerically computed, assuming that it results from the free carrier scattering by the natural plasmon and/or phonon hybrid modes initially introduced by Varga and which self-consistently issue from the full dielectric response of the material. We first develop a physical approach (i) which allows us to find back in a simple way the transition probability which was initially obtained for three-dimensional systems by Kim et al. in the frame of the second quantization formalism and (ii) which allows us to easily extend this formalism to the case of multi subband quantum wells. Then, the full two-dimensional dielectric function and its corresponding scattering potential is numerically computed, allowing us to predict the order of magnitude that can be expected for the low-field intrinsic mobility versus free carrier density in triangular quantum wells. We finally compare this scattering mechanism with the usual extrinsic scattering mechanisms associated with impurities, dislocations, and interface roughness.