Non-Recessed-Gate Enhancement-Mode AlGaN/GaN High Electron Mobility Transistors with High RF Performance

We fabricated non-recessed-gate enhancement-mode (E-mode) AlGaN/GaN high electron mobility transistors (HEMTs) with a gate length L g of 120 nm. As gate metals, Ni/Pt/Au and Mo/Pt/Au were used. The Ni/Pt/Au-gate HEMTs with rapid thermal annealing (RTA) at 500°C were normally-off at a gate-source voltage V gs of 0 V, indicating E-mode operation. Moreover, the Mo/Pt/Au-gate HEMTs also showed E-mode device operation without RTA. The fabricated E-mode HEMTs with both gate metals showed high RF performance. We obtained a cutoff frequency f T of more than 50 GHz and a maximum oscillation frequency f max of approximately 100 GHz.