DC and RF characteristics of type II lineup InAs/AlSb HFETs

Growth, fabrication, and characterization for a type II lineup InAs/AlSb HFET are presented. An as-grown epitaxy wafer with a 300 K mobility of 21,300 cm
²
/V-s and an electron sheet concentration of 1.4times10
¹²
cm
^-2
was processed into devices. Peak transconductance of 720 mS/mm and drain current of 650 mA/mm at drain voltage of 1.0 V are achieved in a 1-mum gate length device. It is observed strong drain bias dependence of both DC drain currents and transconductances, on-state bell-shaped peaks in the gate leakage, and a large dispersion between DC and RF transconductances. Strong impact ionization along with no hole confinement in the InAs channel are suggested attributions for these phenomena.