Analytical Model on the Threshold Voltage of Charge-Trap-Based Hybrid Gate-Stack GaN MIS-HEMT

In this article, we introduce a new analytical model for determining the threshold voltage (${V} {_{\text {TH}}}$) in charge-trap-based hybrid gate-stack enhancement-mode (E-mode) AlGaN/GaN MIS-high electron mobility transistors (HEMTs). The${V} {_{\text {TH}}}$expression is derived by simultaneously solving the potential balance and interfacial Gauss equations based on band and charge distribution analyses, with the stored charge in the charge-trapping layer (CTL) evaluated considering both Wentzel–Kramers–Brillouin (WKB)-based tunneling and thermally activated emission probabilities. The model examines how${V} {_{\text {TH}}}$depends on structural parameters across three CTL thickness regimes: thin, where CTL thickness has minimal effect, but the blocking layer thickness dominates; intermediate, where both CTL thickness and trapped charge influence${V} {_{\text {TH}}}$; and thick, where trapped charge is negligible and${V} {_{\text {TH}}}$decreases linearly with increasing CTL thickness. The model’s accuracy was validated by TCAD simulation, and the dependence of${V} {_{\text {TH}}}$on various initialization voltages and temperature was analyzed. The results offer valuable guidance for optimizing the structure and designing charge-trap-based hybrid gate-stack E-mode GaN MIS-HEMTs.