Effects of Metal-Hydroxyl and InO_{<italic>x</italic>}Defects on Performance of InGaZnO Thin-Film Transistor

The properties of metal-hydroxyl (M-OH) and InO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> defects in InGaZnO (IGZO) and their influences on the performance of IGZO thin-film transistor (TFT) are investigated. The defects in the IGZO film are intentionally modulated by using various postmetallization-annealing (PMA) treatments. PMA is effective to densify the IGZO film and thus suppress the formation of M-OH. On the other hand, the PMA also leads to the formation of InO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> near the edge of conduction channel. It is found that M-OH acts as deep-level acceptor like trap and has a heavy influence on the off-current, threshold voltage, and subthreshold swing of the TFT. On the other hand, InO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> acts as shallow-level donor and mainly affects the carrier mobility of the TFT. The effects of M-OH and InO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> on the TFT performance decrease and increase, respectively, with decreasing the channel length.