Improved Performance of Fully-Recessed High-Threshold-Voltage GaN MIS-HEMT With in Situ H₂/N₂ Plasma Pretreatment

In this letter, we demonstrate a high-threshold-voltage and high-current-density normally-off SiN/AlN/ GaN-on-Si MIS-HEMT with in situ low-damage H ₂ /N ₂ plasma pretreatment. The in situ plasma pretreatment was performed in a plasma enhanced atomic layer deposition (PEALD) system prior to the PEALD-AlN deposition, which effectively suppress the interface trap densities between the AlN/GaN interface and increase the mobility of electrons to 198.80 cm $^{{2}}/\text {V} \cdot \text {s}$ . Therefore, the devices demonstrate state-of-art characteristics with a competitive maximum drain current of 683.75 mA/mm at ${V} _{\textit {GS}} =15\text{V}$ and a high threshold of 6.28 V. The devices also show ON/OFF current ratio of $10^{{8}}$ and off-state breakdown voltage of 1778 V.