Improvement of RF and Noise Characteristics Using a Cavity Structure in InAlAs/InGaAs HEMTs

Reduction of parasitic capacitance in the gate region by adopting a cavity structure improved the high-frequency and noise characteristics of InAlAs/InGaAs high-electron mobility transistors (HEMTs). We achieved a high cutoff frequency f
_T
of 517 GHz and a minimum noise figure NF
_min
of 0.71 dB at 94 GHz even after passivation and interconnection process. Scaling of the gate-to-channel distance and gate-recess length is also effective in enhancing transconductance g
_m
to improve f
_T
and NF
_min
. The cavity structure is a promising candidate that can help in achieving high-performance millimeter-wave monolithic integrated circuits with multilayer interconnections.