First-principles Monte Carlo simulation of electron transport in Al_xGa_1-xN/GaN high-electron-mobility transistors

We simulate semiclassical electron transport in wide-band-gap AlGaN/GaN high-electron-mobility transistors (HEMTs), which are widely studied for their application in power electronics. We perform first-principles calculations to obtain the electronic band structures, the phonon dispersions, and the electron-phonon scattering rates of both GaN and AlN in their wurtzite phase. These properties of the ternary alloy Al_xGa_1-xN are obtained using the virtual crystal approximation starting from GaN and AlN. Applying electrical bias to the Al_xGa_1-xN/GaN HEMTs, we solve the Boltzmann transport equation (BTE) with the Monte Carlo technique. Five conduction bands are employed for electrons’ kinetics, so that electrons with an energy as high as 8 eV can be described. The Poisson’s equation is solved self-consistently with the BTE while performing the device simulation. We obtain the ensemble Monte Carlo particles’ energy distribution. The results are used to study hot-carrier-induced defect activation and to understand the device degradation. The high-field electron transport capability offered by the full-band Monte Carlo technique is demonstrated throughout the present work.