High-energy electron relaxation and full-band electron dynamics in aluminium nitride

Material properties of AIN, particularly its wide band gap around 6eV, warrant its operation in the high-field transport regimes reaching MV/cm fields. In this theoretical work, we examine the full-band scattering of conduction band electrons in AIN due to polar optical phonon (POP) emission, which is the main scattering channel at high fields. First, we obtain the band structure for the wurtzite phase of AIN using the empirical pseudopotential method. Scattering rates along the full length of several hi.-h-symmetry directions are computed efficiently through the Lehmann-Taut Brillouin zone integration technique. In order to shed light on the behaviour of the velocity-field characteristics at extremely high electric fields, in the order of a few MV/cm, we resort to an Esaki-Tsu estimation. Comparison of these results for AIN is made with our similar work on GaN. With typically more than 50% higher POP scattering rate compared to GaN, AIN has poorer high-field prospects. Availability of these data for AIN and GaN paves the way for practical assessment of the high-energy electron dynamics for the ternary alloy, AlGaN. (C) 2002 Elsevier Science B.V. All rights reserved.