Characterization and Reliability Analysis of Enhancement-Mode PEALD AlN/LPCVD SiN_x GaN MISFET with In Situ H₂/N₂ Plasma Pretreatment

An effective in situ H2/N2 pretreatment technique for enhancement-mode GaN MISFET with a PEALD AlN/LPCVD SiNx Dual Gate Dielectric is presented. This technique features in situ H2 (15%)/N2 (85%) plasma pretreatment prior to AlN deposition. By using in situ H2 (15%)/N2 (85%) plasma pretreatment and a PEALD AlN protection layer, combined with an LPCVD SiNx gate dielectric, the quality of the AlN/GaN interface can be further improved due to the reduced interface trap densities between the AlN/GaN interface. The interface protection technique enables the successful integration of a high-quality PEALD AlN/LPCVD SiNx gate dielectric in an E-mode GaN MISFET with high performance, high stability, and high reliability. The fabricated enhancement-mode GaN MISFET exhibits a high gate swing and high channel effective mobility of 187.5 cm2/Vs, a threshold voltage of 2.9 V defined at 1 µA/mm, an on/off current ratio of 108, and a breakdown voltage of 1760 V defined at ID = 10 μm/mm. Our experiments showed a significant reduction in dynamic ON resistance and the suppression of current collapse when using the enhancement-mode GaN MISFET with PEALD AlN/LPCVD SiNx under high drain bias switching conditions, especially when the VDS is greater than the 60 V drain bias switch operating state.