Improved Linearity for Low-Noise Applications in 0.25- $ \mu\hbox{m}$ GaN MISHEMTs Using ALD $\hbox{Al}_{2}\hbox{O}_{3}$ as Gate Dielectric

Improved device linearity for low-noise applications has been demonstrated in 0.25-μm AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs) using atomic-layer-deposited (ALD) Al 2 O 3 as gate dielectric. The measured dc transconductance, microwave small signal, and noise performance feature less dependence on drain current as compared to conventional Schottky-gate AlGaN/GaN HEMTs. Two-tone intermodulation measurement shows that the MISHEMT has a higher value of third-order intercept (IP3). The improved device linearity suggests that the ALD Al 2 O 3 /AlGaN/GaN MISHEMT on high-resistivity silicon substrate is promising for high-linearity low-noise amplifier applications.