Stable high-temperature operation of E/D-mode tri-gate AlGaN/GaN MIS-HEMTs with digital recess technique for monolithic integration

This Letter presents tri-gate GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) with improved high-temperature performance for a monolithic integration platform, utilizing a low-damage digital recess technique. The fin structure followed by the multiple cycles of plasma oxidation and wet oxide removal process enables threshold voltage modulation from −9.1 V (D-mode) to +1.1 V (E-mode) in MIS-HEMTs, achieved by tuning the fin width between 800 and 56 nm on the same wafer. The E-mode device shows a low subthreshold swing of 76 mV/dec, a low on-resistance of 8.2 Ω·mm, and a low hysteresis of 26 mV. The E-mode device exhibits a small threshold voltage (Vth) shift of −0.13 V from room temperature up to 200 °C leading to logic inverters of stable characteristics with an inverter threshold voltage shift of only 0.16 V from 25 to 250 °C. These results validate the monolithic integration of tri-gate GaN to be promising for high-frequency and compact mixed-signal systems.