Microwave Low-Noise Performance of $0.17~\mu \text{m}$ Gate-Length AlGaN/GaN HEMTs on SiC With Wide Head Double-Deck T-Shaped Gate

Microwave low-noise performance AlGaN/GaN HEMT on a SiC substrate with a wide head double-deck T-shaped gate has been reported. The HEMTs with gate-length (
$L_{\mathrm { {g}}})$
of
$0.17~\mu \text{m}$
and source–drain spacing (
$L_{\mathrm { {sd}}})$
of
$3.5~\mu \text{m}$
exhibited a maximum extrinsic transconductance of 360 mS/mm, a current gain cutoff frequency (
$f_{\mathrm { {T}}})$
of 50 GHz, a maximum oscillation frequency (
$f_{\mathrm { {max}}})$
of 149 GHz, and three-terminal breakdown voltage of 113 V. The device exhibited a minimum noise figure (NF
$_{\mathrm { {min}}})$
of 0.50 and 0.84 dB at 10 and 18 GHz, respectively, when biased at
$V_{\mathrm { {ds}}}= 5$
V and
$I_{\mathrm { {ds}}}= 140$
mA/mm, which is the lowest noise characteristics ever reported for the GaN-based T-shaped gate HEMTs with gate length larger than
$0.1~\mu \text{m}$
. This excellent noise performance is attributed to the reduction of the gate resistance resulting from a wide head T-shaped gate and the improved device characteristics.