In this paper, we investigated the structural properties and electrical characteristics of high-kappa ErTixOy gate dielectrics on indium-gallium-zinc oxide thin-film transistors (IGZO TFTs). We used X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy to investigate the structural and morphological features of these dielectric films after they had been subjected to annealing at various temperatures. The high-kappa ErTixOy IGZO TFT device annealed at 400 degrees C exhibited better electrical characteristics in terms of a large field-effect mobility (8.24 cm(2)/V-s), low threshold voltage (0.36 V), small subthreshold swing (130 mV/dec), and high I-on/off ratio(3.73 x 10(6)). These results are attributed to the reduction of the trap states and oxygen vacancies between the ErTixOy film and IGZO active layer interface during high-temperature annealing in oxygen ambient. The reliability of voltage stress also can be improved by the oxygen annealing at 400 degrees C. (C) 2013 Elsevier B.V. All rights reserved.