A development of high quality InxGa1 - xAs epitaxial layers on Si substrates is essential for high-performance logic transistors due to the low fabrication cost and high compatibility with a conventional Si technology. We investigate the surface of In0.53Ga0.47As epitaxial layers grown by metal-organic chemical vapor deposition on a Si substrate (with InP/GaAs buffer layers) to obtain a high capacitance using high-k films (HfO2/Al2O3 bilayer). The high-k films were grown on In0.53Ga0.47As epitaxial layers by atomic layer deposition (ALD). The interface between the high-k bilayer and the In0.53Ga0.47As epitaxial layer was analyzed depending on a surface treatment of the In0.53Ga0.47As epitaxial layer, and the surface treatment of the In0.53Ga0.47As epitaxial layer using trimethylaluminum (TMA) enhanced the electrical performances of Pt/high-k film/In0.53Ga0.47As capacitors. The TMA was introduced on the In0.53Ga0.47As epitaxial layer in the ALD chamber, which reduced native oxides (such as gallium and arsenic oxides) of the In0.53Ga0.47As surface and minimized a formation of interfacial layers between the high-k film and In0.53Ga0.47As layer. A capacitance equivalent thickness (CET) of similar to 1.5 nm was achieved with a low leakage current (similar to 10(-4) A/cm(2) at 1 V). A CET as low as similar to 1.3 nm and a capacitance > 2.5 mu F/cm(2) was attained by optimizing the high-k/In0.53Ga0.47As interface. The TMA treatment on the In0.53Ga0.47As epitaxial layer is compatible with the conventional Si technology and provides promising opportunities for the development of state-of-the-art field-effect transistor technology using InxGa1 (-) As-x epitaxial layers.