Attainment of low interfacial trap density absent of a large midgap peak in In0.2Ga0.8As by Ga2O3(Gd2O3) passivation

The pronounced high interfacial densities of states (D-it) commonly observed around the midgap energy of dielectric/GaAs interfaces are generally considered the culprit responsible for the poor electrical performance of the corresponding inversion-channel metal-oxide-semiconductor field-effect-transistors. In this work, comprehensive D-it spectra as the function of energy (D-it(E)] inside the In0.2Ga0.8As band gap were constructed by using the quasistatic capacitance-voltage and the temperature-dependent conductance method on n- and p-type ultrahigh vacuum (UHV)-Ga2O3(Gd2O3)/In0.2Ga0.8As and atomic-layer-deposited (ALD)-Al2O3/In0.2Ga0.8As metal-oxide-semiconductor capacitors. Unlike the ALD-Al2O3/In0.2Ga0.8As interface giving a D-it spectrum with a high midgap D-it peak, the UHV-Ga2O3(Gd2O3)/In0.2Ga0.8As interface shows a D-it spectrum that monotonically decreases from the valence band to the conduction band with no discernible midgap peak. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554375]