Analytical modeling of channel potential and threshold voltage of triple material gate AlGaN/GaN HEMT including trapped and polarization-induced charges

Abstract

We have developed an analytical model of channel potential and threshold voltage of a gate-engineered heterostructure transistor, triple material gate aluminum gallium nitride (AlGaN)/gallium nitride (GaN) high electron mobility transistor (HEMT). Two steps in channel potential profile lead to suppression of short channel effects. For accurate modeling of the device, spontaneous and piezoelectric polarization-induced charges at the AlGaN/GaN interface and temperature and mole fraction dependence of device parameters are considered. The impact of trapped charges formed because of process defects during device growth is also analyzed. The device performance is studied with the variation in device parameters, and superior performance of triple material gate HEMT over other HEMT structures is observed in terms of reduced short channel effects and enhanced carrier velocity. Results from the proposed analytical model are validated against the data obtained from a commercially available numerical device simulator.