GaAs surface passivation using in-situ oxide deposition

In-site deposition of Ga2O3, SiO2, and MgO films on clean, atomically ordered (100) GaAs surfaces grown by molecular beam epitaxy using a multiple-chamber ultra high vacuum system has been investigated. Using this technique, direct bonding of oxide molecules to GaAs surface atoms revealing intrinsic oxide-GaAs interface properties has been achieved. The GaAs surface reconstruction prior to deposition as observed by reflection high energy electron diffraction and the chemical shift of the interfacial As 3d core level acquired by X-ray photoelectron spectroscopy depth profiling are clearly correlated. AsxOy or elemental As were not detectable at in-situ fabricated oxide-GaAs interfaces. In sharp contrast to SiO2- and MgOGaAs interfaces which are characterized by a Fermi level intrinsically pinned at midgap, Ga2O3GaAs interfaces exhibit unique intrinsic electronic properties including an interface state density and recombination velocity in the mid 1010 cm−2 eV−1 range and of 4500 cm/s, respectively.