High-Performance Oxide TFTs With Co-Sputtered Indium Tin Oxide and Indium-Gallium-Zinc Oxide at Source and Drain Contacts

Abstract

Amorphous indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) have shown significant potential for applicationin transparent and flexible electronicdevices. However, the source and drain (S/D) electrodesof IGZO TFTs with indium tin oxide (ITO) thin films can cause Schottkylike behavior in the output characteristics owing to the formation of a potential barrier between the IGZO and ITO thin films. In this study, we designed and fabricated TFTs by applying a novel ITO S/D electrode layer (375 nm) with co-sputtered IGZO and ITO thin films (125 nm) deposited at room temperature. The proposed TFT exhibits superior electric characteristics (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> = 35.4 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs) compared to those of TFTs with conventional ITO electrodes (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> = 9.1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs) owing to its lower contact and channel resistance and the generation of a surface reaction between S/D and channel layers, creating additional oxygen vacancies at the IGZO channel region. The proposed S/D electrode could be fabricated on a glass substrate at low temperatures (below 200 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> C). The excellent electrical properties of the proposed IGZO TFT are expected to promote the application of TFTs in advanced displays.