The consumption of the surface native oxides is studied during the atomic layer deposition of TiO2 films on GaAs (100) surfaces. Films are deposited at 200 degrees C from tetrakis dimethyl amido titanium and H2O. Transmission electron microscopy data show that the starting surface consists of similar to 2.6 nm of native oxide and X-ray photoelectron spectroscopy indicates a gradual reduction in the thickness of the oxide layer as the thickness of the TiO2 film increases. Approximately 0.1-0.2 nm of arsenic and gallium suboxide is detected at the interface after 250 process cycles. For depositions on etched GaAs surfaces no interfacial oxidation is observed. (C) 2009 Elsevier B.V. All rights reserved.