Abstract:In this work, high-efficiency AlN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) have been fabricated for millimeter wave applications. A 5-nm SiNx insulator is grown in-situ as the gate insulator by metal-organic chemical vapor deposition (MOCVD), contributing to remarkably suppressed gate leakage, interface state density and current collapse. The fabricated MIS-HEMTs exhibit a maximum drain current of 2.2 A/mm at VGS=2 V, an extrinsic peak Gm of 509 mS/mm, and a reverse Schottky gate leakage current of 4.7×10-6 A/mm when VGS = -30 V. Based on a 0.15 um T-shaped gate technology, an fT of 98 GHz and fMAX of 165 GHz were obtained on the SiN/AlN/GaN MIS-HEMTs. Large signal measurement shows that, in a continuous-wave mode, the MIS-HEMTs deliver an output power density (Pout) of 2.3 W/mm associated with a power-added efficiency (PAE) of 45.2 % at 40 GHz, and a Pout (PAE) of 5.2 W/mm (42.2%) when VDS was further increased to 15 V.