Quantum correction in AlGaN/GaN transistor simulations using Modified Local Density Approximation (MLDA)

Highly degenerated and confined Two-Dimensional Electron Gas (2DEG) is the essential part of AlGaN/GaN HEMTs but is usually modeled classically. We studied the application of Modified Local Density Approximation (MLDA) as a quantum correction to 2DEG in AlGaN/GaN HEMTs. It is found that MLDA is an efficient model that does not degrade the convergence behavior with little run time penalty when the Poisson equation and electron/hole continuity equations are solved self-consistently. It is then applied to a power MISFET and a highly scaled N-polar HEMT for RF applications. It is found that by taking the quantum effect into consideration through MLDA, under certain bias conditions, the drain current can be changed by almost 10% and breakdown voltages are increased substantially. The f
_T
can be changed significantly when gate over-drive is not sufficient.