Light-Induced Hysteresis of In–Ga–Zn–O Thin-Film Transistors With Various Temperatures

Abstract

We investigated the hysteresis phenomenon in In-Ga-Zn-O thin-film transistors under light illumination. Hysteresis was observed under the 450-nm illumination and was increased with temperature. Light-induced hysteresis occurs due to increased subband-gap states at the interface between the gate-insulator layer and the active layer. Increased subband-gap states increase the subthreshold slope (SS) during the forward sweep. As temperature increases, the transition rate from neutral oxygen vacancy <i 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">O</sub> to doubly ionized oxygen vacancy <i 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">O</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> increases under the same illumination conditions. The SS of the forward sweep increases with temperature due to the increase in <i 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">O</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> states.