In this paper, we demonstrate high electron mobility In0.53Ga0.47As quantum-well metal oxide semiconductor field effect transistor (MOSFET) structures. The Al2O3 (gate dielectric)/ In0.53Ga0.47As-In0.52Al0.48As (barrier)/In0.53Ga0.47As (channel) structures were fabricated, and the mobility was obtained by Hall measurements. The structures with in-situ chemical vapor deposition (CVD) Al2O3 displayed higher mobility than identical structures fabricated with in situ atomic layer deposition Al2O3, which indicates that CVD process resulted in a lower Al2O3/In0.53Ga0.47As interfacial defect density. A gate bias was applied to the structure with CVD Al2O3, and a peak mobility of 9243 cm2/V s at a carrier density of 2.7 × 1012 cm-2 was demonstrated for the structure with a 4 nm In0.53Ga0.47As-In0.52Al0.48As barrier. A model based on internal phonon scattering and interfacial defect coulomb scattering was developed to explain the experimental data and predict the mobility of In0.53Ga0.47As MOSFET structures.