Modeling the Influence of the Acceptor-Type Trap on the 2DEG Density for GaN MIS-HEMTs

In this article, an analytical model on the influence of the acceptor-type trap on the 2-dimensional electron gas (2DEG) density is proposed for GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). Based on the charge-control method, a numerical analysis of the 2DEG in both the subthreshold and above-threshold regions is carried out with the deep-level and band-tail acceptor-type traps at the AlGaN/insulator interface and the AlGaN/GaN interface. In particular, the influence of the acceptor-type trap on the 2DEG density and the gate-control capability in the subthreshold region is modeled for the first time. The results have shown that the acceptor-type trap plays an important role in weakening the gate-control capability of the 2DEG density in the subthreshold region. The experimental results, together with the modeling and numerical calculations, have shown consistent 2DEG density values under various gate voltages, which verify the proposed model.