Modeling and Analysis of Double Channel GaN HEMTs Using a Physics-Based Analytical Model

In this work, we report the development of a new physics-based analytical model for current and charge characteristics of Double Channel (DC) Gallium Nitride High Electron Mobility Transistors (GaN-HEMTs). The model has at its core the self-consistent calculation of the charge densities, for both upper and lower channels, obtained from a solution of the Schrödinger and Poisson equations. Fermi-Dirac (FD) distribution together with 2D density of states is used for mobile carrier statistics in both the channels. Furthermore, drift-diffusion transport is used to compute the channel current using charge densities at channel extremities. Finally, the model is validated against TCAD simulation and experimental data for a DC-GaN-HEMT. The model, by virtue of its fully physics-based nature, precisely captures the charge screening effect in the lower channel without invoking any empirical clamping functions, unlike prior models, and also possesses the feature of being geometrically scalable.