Surface passivation of III-V compound semiconductors using atomic-layer-deposition-grown Al2O3

Al2O3 was deposited on In0.15Ga0.85As∕GaAs using atomic-layer deposition (ALD). Without any surface preparation or postthermal treatment, excellent electrical properties of Al2O3∕InGaAs∕GaAs heterostructures were obtained, in terms of low electrical leakage current density (10−8 to 10−9A∕cm2) and low interfacial density of states (Dit) in the range of 1012cm−2eV−1. The interfacial reaction and structural properties studied by high-resolution x-ray photoelectron spectroscopy (HRXPS) and high-resolution transmission electron microscopy (HRTEM). The depth profile of HRXPS, using synchrotron radiation beam and low-energy Ar+ sputtering, exhibited no residual arsenic oxides at interface. The removal of the arsenic oxides from Al2O3∕InGaAs heterostructures during the ALD process ensures the Fermi-level unpinning, which was observed in the capacitance-voltage measurements. The HRTEM shows sharp transition from amorphous oxide to single crystalline semiconductor.