Quasi-Normally-Off operation via Selective Area Growth in high-K-insulated GaN MIS-HEMTs

We have fabricated and characterized ZrO2/AlGaN/GaN MIS-HEMTs with "dry-etching free" gate recess structures realized using Selective Area Growth (SAG) of AlGaN barrier on the access regions. The transfer characteristics revealed threshold voltage -0.5 V, suggesting quasi-normally-off operation. In comparison with reference planar HEMTs, the threshold voltage of SAG-HEMTs was shifted by about +5 V towards the positive voltage direction. Moreover, SAG-HEMTs showed almost parallel shift of transfer curves with respect to that of the reference planar devices, suggesting no considerable mobility degradation.