High Microwave-Noise Performance of AlGaN/GaN MISHEMTs on Silicon With $\hbox{Al}_{2}\hbox{O}_{3}$ Gate Insulator Grown by ALD

High microwave-noise performance is realized in AlGaN/GaN metal-insulator semiconductor high-electron mobility transistors (MISHEMTs) on high-resistivity silicon substrate using atomic-layer-deposited (ALD) Al
₂
O
₃
as gate insulator. The ALD Al
₂
O
₃
/AlGaN/GaN MISHEMT with a 0.25- ¿m gate length shows excellent microwave small signal and noise performance. A high current-gain cutoff frequency
fT
of 40 GHz and maximum oscillation frequency
f

_max
of 76 GHz were achieved. At 10 GHz, the device exhibits low minimum-noise figure (NF
_min
) of 1.0 dB together with high associate gain (
Ga
) of 10.5 dB and low equivalent noise resistance (
Rn
) of 29.2 ¿. This is believed to be the first report of a 0.25-¿m gate-length GaN MISHEMT on silicon with such microwave-noise performance. These results indicate that the AlGaN/GaN MISHEMT with ALD Al
₂
O
₃
gate insulator on high-resistivity Si substrate is suitable for microwave low-noise applications.