A self-aligned process for fabricating inversion n-channel metal-oxide-semiconductor field-effect-transistors (MOSFET's) of strained In0.2Ga0.8As on GaAs using TiN as gate metal and Ga2O3(Gd2O3) as high K gate dielectric has been developed. A MOSFET with a 4 pm gate length and a 100 pm gate width exhibits a drain current of 1.5 mA/mm at V-g = 4 V and V-d = 2 V, a low gate leakage of < 10(-7) A/cm(2) at 1 MV/cm, an extrinsic transconductance of 1.7 mS/mm at Vg = 3 V, V-d = 2 V, and an on/off ratio of similar to 10(5) in drain current. For comparison, a TiN/Ga2O3(Gd2O3)/In0.2Ga0.8As MOS diode after rapid thermal annealing (RTA) to high temperatures of 750 degrees C exhibits excellent electrical and structural performances: a low leakage current density of 10(-8)-10(-9) A/cm(2), well-behaved capacitance-voltage (C-V) characteristics giving a high dielectric constant of similar to 16 and a low interfacial density of state of similar to(2 similar to 6) x 10(11) cm(-2) eV(-1), and an atomically sharp smooth Ga2O3(Gd2O3)/In0.2Ga0.8As interface. (C) 2008 Elsevier Ltd. All rights reserved.