High-Performance Bilayer In-Ga–Zn-Sn–O Thin-Film Transistors With Moderate Oxygen Doping at Room Temperature

Bilayer-structured amorphous In–Ga–Zn–Sn–O (a-IGZTO) gallium zinc tin oxide (IGZTO):O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> thin-film transistors (TFTs) were prepared at room temperature instead of requiring high temperature. A high field-effect mobility (μ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>FE</roman></sub>) of 40.4 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sup>/Vs, a small threshold voltage (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>th</roman></sub>) of 0.5 V, and a minor subthreshold swing (SS) of 490 mV/decade were achieved on SiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>/Si substrates by adopting a rational design. In addition, a slight shift of the threshold voltage (Δ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>th</roman></sub>) of 3.1 (-1.5) V was obtained under the gate bias stress test. The research results show that moderate oxygen doping did not form high potential barriers at the channel layer interface and maintained the excellent carrier transport performance of the device, mainly due to the fact that oxygen doping reduces the trap density at the channel layer interface and the surface of IGZTO:O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub>, and reduces these defects through the recombination of oxygen vacancies. The proposed bilayer a-IGZTO/IGZTO:O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><roman>2</roman></sub> TFTs prepared at room temperature with superior electrical characteristics and stability are anticipated to offer a novel and efficient method for attaining high-performance flexible display devices.