Electron mobility in AlN from first principles

Wurtzite aluminum nitride is an ultra-wide band gap semiconductor with a high breakdown field, making it applicable for both deep-UV optoelectronics and high-power applications. It is commonly used alloyed with GaN for ease of doping, but recently progress has been made in controllable doping of pure AlN with low defect concentrations. In this work, we calculate the electron mobility of AlN from first principles to investigate the theoretical upper limit of mobility in this material. We include the effects of electron-phonon and electron-ionized-impurity scattering to accurately model the mobility in a doped semiconductor. The electron-phonon interactions are calculated using density functional perturbation theory and interpolated using maximally localized Wannier functions. We show that the inclusion of quadrupole effects is important for accurate interpolation of the long-range effects of the electron-phonon interaction. The electron mobility is calculated over a range of carrier and ionized impurity concentrations and shows good agreement with the highest reported experimental mobility values.