Cryogenic DC and RF characteristics of InP HEMTs with various drain-side recess lengths

We measured the DC and RF characteristics of InP-based 75-nm-gate In
0.52
Al
0.48
As/In
0.63
Ga
0.37
As HEMTs with various drain-side recess lengths L
rd
's at 300 and 16 K. The kink phenomenon was seen in the current-voltage (I–V) characteristics for all the measured HEMTs at 16 K. The peak cutoff frequency ƒ
T
decreases with increasing L
rd
both at 300 and 16 K. On the other hand, the maximum oscillation frequency ƒ
max
shows very complicated behavior both at 300 and 16 K. We found that there exists the most suitable L
rd
value to increase ƒ
max
at each temperature and/or drain-source voltage V
ds
.