In this work, we fabricated n-In0.53Ga0.47As metal-oxide-semiconductor capacitors (MOSCAPs) with a metal-oxide-semiconductor (MOS) interface of Y2O3/In0.53Ga0.47As. We investigated interfacial properties of the gate stack through the H-2 ambient annealing process in MOSCAPs. We obtained an extremely low interface trap density of D-it = 1.8 x 10(11) cm(-2) eV(-1). We compared the H-2 annealing effect in different gate electrode materials of Ni and Pt. We determined that the Pt electrode was effective in maximizing the impact of H-2 annealing. Also, we fabricated In0.53Ga0.47As-on-insulator MOS field-effect-transistors using an optimized annealing process, which showed more stable electrical characteristics than devices through the N-2 ambient annealing process.