Notable improvements in the HfO2/In0.53 Ga0.47As gate stack have been achieved by a post- HfO2 fluorine plasma treatment, including excellent interface quality of low equivalent oxide thickness HfO2 (1.4 nm) directly on In0.53Ga0.47As without using an interface passivation layer, ~ 5× reduction in interface trap density from 2.8 ×1012 to 4.9 ×1011 cm-2eV-1, ~ 10× reduced border traps from 1.6 ×1019 to 1.6 ×1018 cm-3, and ~ 40% less charge-trapping centers. As a result, improved electrical performances have been obtained. Frequency dispersion in capacitance-voltage characteristics has been reduced. Subthreshold swing has been improved from 127 to 109 mV/dec. Effective channel mobility has been enhanced from 826 to 1067 cm2/Vs. An improved drive current of 123 mA/mm at Vd = 2.5 V and Vg - Vth = 2 V (5- μm channel length) has been also presented.