Plasma enhanced atomic layer deposition (PEALD) aluminum nitride (AlN) is attracting great interests as an advanced technique for high-k/III-V interfacial passivation. In this study, we demonstrate the effects of PEALD-AlN layer deposition plasma powers on the electrical properties of both n-type and p-type In0.53Ga0.47As based metal oxide semiconductor capacitors (MOSCAPs). By using PEALD-AlN as interfacial passivation layer (IPL) at the Al2O3/n, p-In0.53Ga0.47As interface, noticeable enhancement of electrical characteristics including small capacitance-voltage (C-V) hysteresis, small frequency dispersion values, and low interface state densities (Dit) have been observed. After performing 5 cycles of PEALD-AlN IPL at optimized plasma power of 150 W, multifrequency C-V responses exhibit excellent behaviors for both n-type and p-type Al 2O3/AlN/In0.53Ga0.47As MOSCAPs. The Dit values are extracted to be 5.3 × 1011-1.2 × 10 12 cm-2 eV-1 and 1.6 × 10 11-2.7 × 1011 cm-2 eV-1 at the trap energy level of 0.47-0.4 eV and 0.2-0.26 eV above the edge of valence band (EV) for n-type and p-type MOSCAPs, respectively. X-ray photoelectron spectroscopy (XPS) analysis reveals that the enhancement of D it values cannot be fully explained by the reduction of native oxides at the InGaAs surfaces. The original reason of interface defects states is attributed to the surface dangling bonds that were passivated by the polycrystalline PEALD-AlN passivation layer as illustrated in the high resolution transmission electron microscopy (HRTEM) image.