Analytical model for 2DEG charge density in β-(Al x Ga1−x )2O3/Ga2O3 HFET

Abstract

In this paper, a physics-based analytical model for two-dimensional electron gas (2DEG) charge density (n s) and pinch-off voltage (V off) in -(Al x Ga1−x )2O3/Ga2O3 heterostructure field effect transistor (HFET) is reported. The modeling approach includes solving the Poisson–Schrödinger equation in -(Al x Ga1−x )O3 barrier layer followed by using standard Fermi–Dirac statistics equations for calculating 2DEG charge density in the potential well. The developed model is then used to analyze the effect of Al composition (x) and barrier thickness (d) of -(Al x Ga1−x )2O3 layer on 2DEG charge density. The obtained parameters from our model for charge density and pinch-off voltages are validated with the experimental results in the literature demonstrating a good accuracy. It was observed that the 2DEG charge density increases with Al composition and Al x Ga1−x O barrier layer thickness, but at the cost of increased pinch off voltage. A trade-off between both is necessary to achieve parametric optimization of -(Al x Ga1−x )2O3/Ga2O3 HFET. This model will be useful to study the various parametric constraints for device optimization in terms of 2DEG charge density and pinch off voltage.