Apparent high mobility ∼30 cm2/Vs of amorphous In-Ga-Zn-O thin-film transistor and its origin

Abstract

Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) annealed in ozone at 250°C exhibited a good subthreshold swing (S) of 123 mV/decade and a saturation mobility (μsat) of ∼10 cm2/Vs, but a bit large threshold voltage (Vth) of 11.6V. Further oxygen annealing at 200°C resulted in high apparent μsat of ∼30 cm 2/Vs and deteriorated characteristics such as a large S value and large hysteresis. The high apparent μsat values were attributed to the electrical discharge between the gate and source electrodes. Reasonably actual μsat values ∼10 cm2/Vs were obtained using the actual capacitance calculated from the discharge characteristics. © 2013 The Ceramic Society of Japan. All rights reserved.