Annealing Strategy Toward Achieving High-Performance Indium Tungsten Oxide Thin-Film Transistors by Equilibrating Oxygen Vacancy and Chemisorbed Oxygen

Abstract

High-performance thin-film transistors (TFTs) are crucial for advanced displays. The use of metal oxide (MO) as an excellent semiconductor to achieve high-mobility TFTs comes with certain challenges, such as a severely negative threshold voltage ( ${V} _{th}$ ) and instability. These issues are attributed to defects and impurities within MO thin films, specifically oxygen vacancies and chemisorbed oxygens. Addressing these challenges is essential, prompting a study on improved fabrication strategies. In this work, we investigated annealing strategies to enhance the performance of indium tungsten oxide (IWO) TFTs. A two-step annealing approach was proposed to balance the concentration of oxygen vacancies and chemisorbed oxygens. This method effectively boosted the field-effect mobility ( $\mu _{FE}$ ) of IWO TFTs to 58 cm2/Vs, concurrently achieving a small negative ${V} _{th}$ of −3.5 V and a favorable subthreshold swing (SS) of 0.35 V/dec. The proposed mechanism was validated through technology computer-aided design (TCAD) device simulation and low-frequency noise (LFN) analysis. The law of annealing IWO TFTs was analyzed based on the results obtained from postannealing experiments conducted at variable temperatures. The entirety of the experimental findings and conclusions is anticipated to provide valuable insights for the fabrication of high-mobility IWO TFTs.