Full band Monte Carlo simulation of high field transport in AlGaN: Ab-initio approach using supercells

Over the past decade, wide bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors, particularly III-nitrides, have gained significant attention for next-generation power and RF electronics. Among them, AlₓGa₁₋ₓN alloys offer extensive scope for device design due to their tunable bandgap ranging from 3.4 to 6.2 eV. Despite several reports of AlGaN-based power and RF devices, their performance has yet to reach the material’s theoretical limits. To fully realize this potential, it is essential to understand high-field transport mechanisms and transient carrier dynamics. In this work, we investigate electron transport in bulk AlGaN using first-principles calculations combined with full-band Monte Carlo simulations. Supercell-based methods are employed to capture true alloy disorder, instead of traditional methods like Virtual Crystal Approximation. Electronic and Phonon Band structures are computed using DFT and DFPT, and all ab-initio scattering mechanisms are included across eight conduction bands up to 4 eV from the conduction band minima. Our simulations reveal the velocity–field characteristics, transient dynamics, and the role of alloy scattering under high electric fields, offering key insights for scaling and optimizing AlGaN-based RF devices.