Considerable on-state impact ionization and off-state tunneling leakages are the two principal drawbacks of InAs/AlSb HEMTs, which have a small bandgap and type-II band lineup. This work introduced a wide-bandgap high-k Al(2)O(3) between the gate metal and semiconductor surface and successfully demonstrated DC and RF performance of the InAs/AlSb metal-oxide-semiconductor HEMTs (MOS-HEMTs). An MOS-HEMT device with a 2.0 mu m gate length yields DC performance of I(DSS) = 286 mA/mm and G(m) = 495 mS/ mm and RF performance of f(T) = 10.1 GHz and f(MAX) = 19.9 GHz. Compared with a conventional HEMT, gate leakage is reduced by one order and the marked dependence of drain current on gate bias in the deep subthreshold region is largely alleviated. (C) 2010 Elsevier Ltd. All rights reserved.