N₂O treatment enhancement-mode InAlN/GaN HEMTs with HfZrO₂ High-k insulator

A normally-off InAlN/GaN MIS-HEMT with HfZrO₂ gate insulator was realized and investigated. By using N₂O plasma treatment beneath the gate region, 13 nm InAlN Schottky layer was oxidized to AlON_x + 4 nm InAlN Schottky layer. The strong polarization induced carriers in traditional InAlN/GaN 2 DEG quantum well was reduced for enhancement-mode operation. High-k thin film HfZrO₂ was used for gate insulator of E-mode device to further suppress gate leakage current and enhance device gate operation range. The maximum drain current of E-mode InAlN/GaN MIS-HEMT was 498 mA/mm and this value was higher than previous published InAlN/GaN E-mode devices. The measurement results of low-frequency noise also concluded that the low frequency noise is attributed to the mobility fluctuation of the channel and N₂O plasma treatment did not increase fluctuation center of gate electrode.