Effect of Al2O3 Passivation Layer and Cu Electrodes on High Mobility of Amorphous IZO TFT

Abstract

In this paper, we present a high mobility amorphous indium-zinc-oxide (a-IZO) thin film transistor (TFT) based on copper (Cu) source/drain electrodes (S/D) and aluminum oxide (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) passivation layer (PVL). The mechanism of high mobility for the a-IZO TFT based on Cu S/D with Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL was proposed and experimentally demonstrated. The sputtering of Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL induced a highly conductive channel layer due to the formation of In-rich layer on the back channel. Also, Cu S/D presented Schottky contact behavior compared with Mo S/D which behaved like Ohmic contact. Because the Schottky contact can block leakage current and the highly conductive channel achieved high on-current, the a-IZO TFT based on Cu S/D and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PVL performed remarkable saturation mobility up to 412.7 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs. This paper presents a feasible way to implement high mobility TFT arrays with Cu electrodes.