Fabrication of Transparent TiO2−x Channel-Based Thin Film Transistors using an Oxygen-Deficient TiO2−x Target

Abstract

We report fabrication of an amorphous TiO2−x (a-TiO2−x) channel based oxide thin film transistor (OxTFT) by direct-current magnetron sputtering using an oxygen-deficient TiO2−x target. By rapid thermal annealing of a sputtered TiO2−x channel layer in nitrogen ambient, we obtained a-TiO2−x-based OxTFTs with a performance of μFE of 0.69 cm2/Vs, Ion/off of 2.04 × 107, SS of 2.45 V/decade and VT of 10.45 V. X-ray photoelectron spectroscopy showed that the a-TiO2−x-based OxTFT performance could be attributed to the oxygen-deficient TiO2−x channel layer, which has a multiplicity of Ti oxidation states such as Ti2+, Ti3+ and Ti4+ unlike stoichiometric TiO2 film. This indicated that the sputtered a-TiO2−x channel layer is a promising indium-free or gallium free oxide channel layer that could substitute for high-cost indium or gallium oxide based channel layers to generate cost-efficient OxTFTs.