Exploring the impact of AlGaN barrier thickness and temperature on normally-on GaN HEMT performance

Abstract

Theoretical studies are conducted on varying barrier thicknesses in GaN/AlGaN HEMTs, as well as the effect of temperature fluctuation on device functionality. Structures A, B, C, D and E are designed each with barrier thickness 16 nm, 19 nm, 22 nm, 25 nm, and 28 nm respectively. A theoretical model is explained that helps to understand the impacts of barrier thickness variation on surface barrier height, strain relaxation and 2DEG concentration. The concept is further expanded to include the GaN HEMT's drain and transfer properties. Investigations are also done on how different thermal impacts affect the functionality of the device. We contemplate alloy disorder, interfaceroughness (IFR) as well as polar-optical phonon scattering. At elevated temperatures, the polar-optical phonon dispersion is the predominant process. Yet, at lower temperatures, the IFR and alloy disorder dispersion both satisfactorily account for the reported mobilities.