Hybrid p-GaN/MIS Gate HEMT Suppressing Drain-Induced Dynamic Threshold Voltage Instability

This letter demonstrates a hybrid p-GaN/MIS gate HEMT (HG-HEMT) to suppress the drain-induced dynamic threshold voltage ( <tex-math notation="LaTeX">Vₜₕ) </tex-math> instability. By implementing a depletion-mode (D-mode) MIS gate adjacent to Schottky-type p-GaN gate, the drain-induced bidirectional shift of dynamic <tex-math notation="LaTeX">Vₜₕ </tex-math> is significantly reduced. The fabricated HG-HEMT exhibits decent performances compared to the conventional Schottky-type p-GaN gate HEMT (Conv-HEMT), with saturation current ( <tex-math notation="LaTeX">I_ D, sat) </tex-math> of 345 mA/mm, on-resistance ( <tex-math notation="LaTeX">RON) </tex-math> of <tex-math notation="LaTeX">13.2~Ω · </tex-math> mm, and hard breakdown voltage (BV) of 1315 V, which are similar to the Conv-HEMT. The HG-HEMT demonstrates significantly improved dynamic <tex-math notation="LaTeX">Vₜₕ </tex-math> stability under drain bias, with a negligible dynamic <tex-math notation="LaTeX">Vₜₕ </tex-math> shift at on-state drain bias of 50 V, and a small positive dynamic <tex-math notation="LaTeX">Vₜₕ </tex-math> shift of +0.05 V after off-state drain bias of 400 V. As a comparison, <tex-math notation="LaTeX">Vₜₕ </tex-math> shifts of the Conv-HEMT are −0.28 V and +0.42 V, respectively. The improved dynamic <tex-math notation="LaTeX">Vₜₕ </tex-math> stability of the HG-HEMT is owing to a D-mode MIS-gate region that shields the interplay between drain and the p-GaN region. The proposed HG-HEMT paves the way for highly stable GaN power electronics applications.