Steady-state and transient electronic transport properties of β-(Al _x Ga_1–x )₂O₃/Ga₂O₃ heterostructures: An ensemble Monte Carlo simulation

Abstract

The steady-state and transient electron transport properties of β-(Al x Ga1−x )2O3/Ga2O3 heterostructures were investigated by Monte Carlo simulation with the classic three-valley model. In particular, the electronic band structures were acquired by first-principles calculations, which could provide precise parameters for calculating the transport properties of the two-dimensional electron gas (2DEG), and the quantization effect was considered in the Γ valley with the five lowest subbands. Wave functions and energy eigenvalues were obtained by iteration of the Schrödinger–Poisson equations to calculate the 2DEG scattering rates with five main scattering mechanisms considered. The simulated low-field electron mobilities agree well with the experimental results, thus confirming the effectiveness of our models. The results show that the room temperature electron mobility of the β-(Al0.188Ga0.812)2O3/Ga2O3 heterostructure at 10 kV⋅cm−1 is approximately 153.669 cm2⋅V−1⋅s−1, and polar optical phonon scattering would have a significant impact on the mobility properties at this time. The region of negative differential mobility, overshoot of the transient electron velocity and negative diffusion coefficients are also observed when the electric field increases to the corresponding threshold value or even exceeds it. This work offers significant parameters for the β-(Al x Ga1−x )2O3/Ga2O3 heterostructure that may benefit the design of high-performance β-(Al x Ga1−x )2O3/Ga2O3 heterostructure-based devices.