Electron-Phonon Scattering and Mobility in Atomically Thin AlN/GaN Superlattices from First Principles

Alloy scattering is stronger than electron-phonon scattering in random AlGaN alloys, resulting in poor mobility compared to the ideal "virtual" alloys of GaN and AlN. In this work, we investigate the phonon-limited electron mobility of atomically thin AlN/GaN superlattices using density-functional perturbation theory and many-body perturbation theory. The superlattices exhibit increased electron mobility and power-electronics figure of merit compared to random AlGaN alloys due to the absence of alloy scattering. Although random alloys are poorly described by virtual crystals, we find that key transport-related properties of the atomically thin superlattices are accurately described by a composition-dependent linear interpolation of the end binary compounds. Therefore, the replacement of a random solid solution with an atomically thin superlattice could be a general strategy for increasing the mobility of compounds for which alloy scattering dominates electron-phonon scattering.