Physics-Based Models of 2DEG Density and Gate Capacitance for p-GaN/AlGaN/GaN Heterostructure

Physics-based analytical model of 2-D electron gas (2DEG) density is proposed for p-GaN/AlGaN/GaN heterostructure considering the thermionic field emission (TFE) of holes through gate metal/p-GaN Schottky junction and hole thermionic emission (TE) over the AlGaN barrier. Besides, the proposed model also takes into account the effect of interface traps and depletion charge in the unintentionally doped (UID)-GaN layer. Formulation of this 2DEG charge is further extended to model the gate capacitance for the same heterostructure. The proposed models are rigorously validated with experimental and/or simulation results for a wide range of gate bias and device parameters. The accuracy of the core model is further verified by comparing the variation of internal potential distribution across various layers of the heterostructure with TCAD results over a broad range of gate biases.