700 V/2.5 A Normally-off Ultrathin-barrier AlGaN(<6nm)/GaN MIS-HEMTs with Improved Gate Overdrive Window and PBTI

700 V/2.5 A enhancement-mode (E-mode) ultrathin-barrier (UTB)-AlGaN (<6nm)/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) device was demonstrated on 6-inch GaN-on-Si wafers without AlGaN barrier recess. A combination of plasma-enhanced atomic-layer-deposited (PEALD) AlN and low-pressure chemical-vapor-deposited (LPCVD) SiN x passivation layer is adopted for the recovery of the two-dimensional electron gas (2DEG) in the access region of the E-mode UTB-AlGaN/GaN MIS-HEMTs. Compared to a controlled MOS-Channel-HEMT (MOSC-HEMT) with a fully recessed gate, the fabricated AlGaN-recess-free E-mode GaN-on-Si MIS-HEMTs exhibit a threshold voltage ( $V_{\text{TH}}$ ) of 0.1 V with good uniformity, a maximum drain current of 2.5 A, and a breakdown voltage over 700 V. The device also features a decent gate overdrive window and positive bias temperature instability (PBTI). The UTB-AlGaN/GaN-on-Si technology platform is highly preferred for an AlGaN-recess-free fabrication and integration of GaN-based power devices and ICs.