In situ hydrogen and nitrogen radicals surface modification of aluminum gallium nitride for high-performance aluminum gallium Nitride/Gallium nitride MIS-HEMTs fabrication

A radical-based surface treatment technique was developed for high performance Al₂O₃/AlGaN/GaN MIS HEMTs fabrication. In-situ H and N radicals were used on AlGaN surface to remove the surface native oxides, restore nitrogen vacancies, and passivate surface states. With the radicals surface treatment, the interface states ($D_{it}$) of Al₂O₃/AlGaN were reduced by approximately one order of magnitude. Consequently, the manufactured MIS HEMT demonstrated excellent performances: stable threshold voltage ($V_{TH}$) characteristics, high on/off current ratio ($I_{ON}/I_{OFF}$) of up to ${10}^8$, gate leakage current as low as 1nA/mm, minimal current collapse, and under a drain voltage stress of 100 V, the increase in dynamic on-state resistance improves from approximately 240 % to around 30 %. Furthermore, from the perspectives of surface morphology and channel mobility, the radicals surface treatment process appears to be non-destructive, which may be attributed to the avoidance of damage from charged particle bombardment, showcasing its great potential for high-performance AlGaN/GaN HEMTs fabrication.