Effects of SiON/III-nitride interface properties on device performances of GaN-based power field-effect transistors

In this work, we performed an investigation on the electrical characteristics of the interfaces of SiON/AlGaN and SiON/GaN by fabricating a partially gate-recessed metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) and a fully gate-recessed metal-insulator-semiconductor field-effect transistor (MIS-FET). The fabricated MIS-HEMT exhibits a smaller static on-resistance (R-on) of 12.7 omega center dot mm, while the MIS-FET achieves the normally-off operation. As a result of over-etching in the gate trench, a higher trap state density of 2 x 10(13) cm(-2)eV(-1) at the SiON/GaN interface in comparison to SiON/AlGaN interface (8 x 10(12) cm(-2)eV(-1)), leading to a more obvious degradation of subthreshold swing, was extracted after performing the high temperature I-DS-V-GS tests. In addition, compared with the MIS-FET, the traps distributed at the SiON/AlGaN interface are found to be located at a deeper energy level, which make the device more stress sensitive and can cause a greater threshold voltage (V-th) shift in the drain-bias stress measurement. The drain-bias stress at off-state increases the ionized trap density and makes the ionized traps unrecoverable within 1000 s in the MIS-HEMT. This work reveals the different properties of traps states at the SiON/AlGaN and SiON/GaN interfaces, and their effects on the device reliability.