Fig. 1. (a) The schematic of epitaxial structure of AlN/GaN MIS-HEMTs, (b) the SEM of 0.15-μm T-gate

Fig. 2. Measured dc characteristics of devices (a) I_D of both HEMTs and MIS-HEMTs versus V_DS with V_GS varied from -6 V to 2 V, (b) gate leakage of HEMTs and MIS-HEMTs with V_GS swept to -30 V, (c) I_D and extrinsic transconductance of MIS-HEMTs with V_GS varied from -6 V to 2 V at V_DS= 6 V, (d) I_D and extrinsic transconductance of HEMTs with V_GS varied from -6 V to 3 V at V_DS= 6 V

Fig. 3. Small-signal characteristics of the fabricated AlN/GaN MIS-HEMTs at V_DS = 10 V

Fig. 4. f/T-dependent C-V characteristics of AlN/GaN MIS-HEMTs with (a) f_m varying from 1 KHz to 1 MHz, (b) T increasing from -25 ℃ to 150 ℃ f_m varying at 10 KHz and 20 KHz (c) D_it-E_T mapping in AlN/GaN MIS-HEMTs

Fig. 5. Pulsed I-V characteristics of (a) output characteristics measured at V_GS = 0 V, (b) transfer characteristics measured at V_DS = 10 V

Fig. 6. Large-signal measurements at 40 GHz in CW mode (a) VDS=8 V, AlN/GaN MIS-HEMTs measurement, (b) VDS=8 V, AlGaN/GaN HEMTs measurement, (c) VDS=10 V, AlN/GaN MIS-HEMTs measurement, (d) VDS=10 V, AlGaN/GaN HEMTs measurement, (e) VDS=15 V, AlN/GaN MIS-HEMTs large-signal measurement, (f) VDS=15 V, AlGaN/GaN HEMTs measurement