In this work, the band alignment, interface, and electrical characteristics of HfO 2 /InSb metal-oxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 ± 0.1 eV and valence band offset of 3.35 ± 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO 2 layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO 2 /InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10 -4 A/cm -2 . The D it value of smaller than 10 12 eV -1 cm -2 has been obtained using conduction method.