N-Face Metal–Insulator–Semiconductor High-Electron-Mobility Transistors With AlN Back-Barrier

We present a high-performance SiN/AlGaN (cap)/GaN (channel)/AlN (barrier)/GaN (buffer) metal-insulator-semiconductor high-electron-mobility transistor grown on the N-face, in which the 2-D electron gas (2DEG) is induced at the top GaN/AlN interface. The use of AlN eliminates alloy disorder scattering to the 2DEG and provides strong back-barrier confinement of the 2DEG under high electric fields for device scaling. Devices with 0.7-mum gate length showed a current-gain cutoff frequency (
fT
) of 17 GHz and a power-gain cutoff frequency (
f

_max
) of 37 GHz. A continuous-wave output power density of 7.1 W/mm was measured at 4 GHz, with 58% power-added efficiency and a large-signal gain of 15.3 dB at a drain bias of 35 V.