Unpinned Interface between Al₂O₃ Gate Dielectric Layer Grown by Atomic Layer Deposition and Chemically Treated n-In _0.53Ga_0.47As (001)

An unpinned interface between an Al₂O₃ layer deposited by atomic layer deposition (ALD) and a chemically treated n-In _0.53Ga_0.47As (001) is demonstrated. The starting surface was prepared by wet etching with NH₄ OH (aq) followed by a thermal desorption of residual As at 380°C immediately before ALD. Analysis of temperature-dependent capacitance-voltage measurements suggests that the Fermi level can sweep through the bandgap of In_0.53Ga_0.47As, attaining true accumulation and inversion despite the presence of In oxide and In hydroxide at the interface. This is in contrast to the situation for residual As-related interfacial species, which have been reported to pin the Fermi level at oxide/III-V interfaces.