Modeling the effect of thin gate insulators (SiO2, SiN, Al2O3 and HfO2) on AlGaN/GaN HEMT forward characteristics grown on Si, sapphire and SiC

Abstract

GaN-based high electron mobility transistors (HEMTs) with a Schottky metal gate have been demonstrated to be an excellent candidate for high frequency, high temperature and high power applications. Nevertheless, their typical (and virtually inevitable) high gate leakage current, severely limits gate voltage swing, output power and breakdown voltage. GaN metal–insulator –semiconductor HEMTs or MIS-HEMTs (formed by introducing a thin dielectric film between the gate metal and semiconductor) is one of the effective solutions that reduce gate leakage and improve device performance. In this work, we evaluate the effect that the introduction of this gate insulator has on the on-state of the HEMT. For this reason, we develop a complete set of compact closed-form expressions for the evaluation of on-resistance, drain and saturation current and transconductance for a MIS-HEMT. This physical-based model describes the mobility in a 2D electron gas channel by means of optical phonon scattering and is explored with insulators based on SiO2, SiNx, Al2O3, and HfO2.