High-Efficiency AlN/GaN HEMTs With High-Quality Stacked Gate Dielectrics on Si Substrate for K- and Ka-Band Applications

In this article, we report high-performance AlN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) fabricated on 6-in Si substrate for K-and Ka-band applications, featuring optimized Al₂2O₃/in situ SiN stacked gate dielectric. The MIS-HEMTs featuring a gate length of 0.2 μm and a drain–source spacing of 3 μm exhibited remarkable electrical characteristics and excellent interface quality, as verified by frequency-dependent capacitance–voltage (C–V) mea-surements. Moreover, device reliability was confirmed through stress testing. Under large-signal radio frequency (RF) operation at 18 GHz, the MIS-HEMTs demonstrated power-added efficiency (PAE) exceeding 75% with drain voltage (V_DS) of 8 V. While at 29 GHz and V_DS = 8 V, the devices achieved a PAE of 68% accompanied by power density of 1.2 W/mm. These exceptional results demonstrate the strong potential of the Al₂O₃/in situ SiN/AlN/GaN MIS-HEMTs on Si for high-efficiency power amplification in K-and Ka-band communication systems.