Efficient Modeling of Barrier Resistance for an Improved Lumped Element Model of GaN-Based MIS-HEMT Gate Stack

Abstract

A methodology has been proposed to accurately model the gate stack of Gallium Nitride (GaN) based metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). Small-signal analysis has been performed for the device biased in the spill-over region, where electrons accumulate at the insulator/III-Nitride ’critical’ interface. Accounting for the barrier layer resistance with an accurate model yields a near but inexact match between simulation and measurement. It is found that the border trap admittance and the energy distribution of the interface trap capture cross section ( $\sigma $ ) need to be included in order to achieve a very close one. It is concluded that the interface trap density, extracted using conventional small-signal admittance methods, can be significantly off if these non-ideal effects are not incorporated within the equivalent circuit models of GaN-based MIS-HEMTs.