RF Performance of Al 0.85 Ga 0.15 N/Al 0.70 Ga 0.30 N High Electron Mobility Transistors With 80-nm Gates

Al-rich AlGaN-channel high electron mobility transistors with 80-nm long gates and 85% (70%) Al in the barrier (channel) were evaluated for RF performance. The dc characteristics include a maximum current of 160 mA/mm with a transconductance of 24 mS/mm, limited by source and drain contacts, and an on/off current ratio of $10^{{9}}$ . ${f}_{T}$ of 28.4 GHz and ${f}_{\text {MAX}}$ of 18.5 GHz were determined from small-signal S-parameter measurements. Output power density of 0.38 W/mm was realized at 3 GHz in a power sweep using on-wafer load pull techniques.