Annealing Strategy Toward Achieving High-Performance Indium Tungsten Oxide Thin-Film Transistors by Equilibrating Oxygen Vacancy and Chemisorbed Oxygen
Zhiying Chen, Yan Yan, Guanglong Ding, Ye Zhou, Su‐Ting Han, Meng Zhang
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 ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{th}}$</tex-math> </inline-formula> ) 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 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu_{{FE}}$</tex-math> </inline-formula> ) of IWO TFTs to 58 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{2}}$</tex-math> </inline-formula> /Vs, concurrently achieving a small negative <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{th}}$</tex-math> </inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 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.