A Novel Physics-Based Approach to Analyze and Model E-Mode p-GaN Power HEMTs

In this article, a physics-based analytical model which considers the channel charge ( Q
_ch
) for enhancement-mode p-GaN power high-electron-mobility transistors (HEMTs) is developed. First, by considering the same dynamic channel charge ( dQ
_ch
) for the Schottky/p-GaN junction capacitance ( C
_j,Sch
) and the p-i-n-junction capacitance ( C
_p-i-n
), due to the p-GaN/AlGaN junction and two-dimensional electron gas (2DEG) charge, the analytical formula to calculate the voltage drop in the p-GaN layer ( V
_pGaN
) is presented. Second, by implementing the analytical formulae in the advanced SPICE model (ASM) GaN model, the proposed physics-based model reliably fits the measured C- V and I
_D
- V
_G
characteristics of the samples under different processing conditions. This provides significant insight regarding the Mg concentration, the voltage drop at the Schottky metal/p-GaN junction ( V
_j,Sch
), and the voltage drop at the p-GaN/AlGaN junction ( V
_p-i-n
). Finally, the I
_D
- V
_G
and I
_D
- V
_D
characteristics of enhancement-mode p-GaN power HEMTs are modeled, displaying good agreement with the experimental data.