Based on sulphur passivation (10% (NH 4 ) 2 S, 20min), the interface of MOS capacitors between atomic-layer-deposited Al 2 O 3 and (110)-oriented p-type In 0.53 Ga 0.47 As layers indicate the capability of Fermi level movement and minority carrier inversion. C ox has effectively extracted by G m /ω & − ωdC/dω. Forming gas annealing (N 2 :H 2 5%:95% at 350°C, 30min) improves minority carrier response and the interface trap density around the midgap estimated to be 4.4×10 12 (1.6×10 12 ) cm −2 eV −1 before (and after) FGA. Moreover, Fowler-Nordheim (FN) tunneling current provides the conduction band offset at the surface between Al 2 O 3 and In 0.53 Ga 0.47 As (110)-oriented layer is ∼1.81eV and the barrier height is estimated to be the same after FGA. Finally, the band parameter of Al 2 O 3 and In 0.53 Ga 0.47 As (110)-oriented layer has been firstly reported