Structural and electrical characteristics of high-κ ErTixOy gate dielectrics on InGaZnO thin-film transistors

Abstract

In this paper, we investigated the structural properties and electrical characteristics of high-κ 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-κ ErTixOy IGZO TFT device annealed at 400°C exhibited better electrical characteristics in terms of a large field-effect mobility (8.24cm2/V-s), low threshold voltage (0.36V), small subthreshold swing (130mV/dec), and high Ion/off ratio(3.73×106). 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°C.