N-Polar GaN MIS-HEMTs on Sapphire With High Combination of Power Gain Cutoff Frequency and Three-Terminal Breakdown Voltage

Nitrogen polar SiNx/AlGaN/GaN/AlGaN metal- insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with 28.6-nm equivalent GaN channel thickness grown by metal-organic chemical vapor deposition on sapphire substrate with a high combination of current/power gain cutoff frequencies (fT/fmax) and three-terminal breakdown voltage (BVDS) are demonstrated. fT/BVDSof 103 GHz/114 V and fmax/BVDSof 248 GHz/114 V were achieved in devices with the gate widths of 2 × 50 μm and 2 × 25 μm, respectively, comparing well with recent reports of fully passivated and vertically scaled Ga-polar GaN HEMTs. Devices with a gate width of 2 × 75 μm showed the peak output power densities of 5.74 W/mm at 4 GHz and 6.29 W/mm at 10 GHz obtained by load-pull measurements.