2.7 kV E-Mode Multichannel GaN-on-Si Based on p-Type NiO/SiO2 Junction Tri-Gate

Abstract

In this work, an E-mode multichannel HEMT is demonstrated based on p-type NiO/SiO2 as a gate stack to form a junction tri-gate structure. NiO provides a high hole concentration ( $\approx ~10^{{19}}$ cm ${}^{-{3}}$ ), resulting in an effective depletion of electrons in the multiple 2DEG channels under the gate. A thin SiO2 layer acts as a sacrificial layer, preventing damage to the fins during NiO deposition. As a result, E-mode operation can be achieved with 3x-larger tri-gate fins, compared to SiO2 alone, with ${V}_{\text {th}}$ of 0.7 V (at $1~\mu $ A/mm), negligible threshold voltage hysteresis ( $\Delta {V}_{\text {th}}$ of 0.05 V), together with small on-resistance ( ${R}_{\text {ON}}$ ) of 2.8 m $\Omega \cdot $ cm2 for a gate-to-drain separation ( ${L}_{\text {GD}}$ ) of $20~\mu $ m. In addition, the devices showed exceptional off-state characteristics, including breakdown voltage ( ${V}_{\text {br}}$ ) of 2.7 kV, and ON/OFF current ratio of $10^{{9}}$ , showcasing the potential of the p-NiO/SiO2 gate stack for high-performance E-mode power devices.