Kousaku Shimizu1
Nihon University1
High-quality p-type Thin Film Transistors have drawn considerable attention for switching elements in active matrix displays such as OLEDs and LCDs. We are investigating sputtered amorphous p-MoS<sub>2</sub> thin films for one of the good candidates. Hot-wire oxidization and sulfur annealing have been done to improve TFT performances. Raman spectroscopy and XPS were employed to characterize the film structure and compared with Id-Vg characteristics.<br/>The sputtered amorphous MoS<sub>2</sub> is generally p-type[1], and the film consists of a stack of small two-dimensional MoS<sub>2</sub> pieces. To reduce the valence mismatch between metals and MoS<sub>2</sub>, Cr/Cu double-layered electrode was employed. According to the TFT simulations, ATLAS, the mobility of TFT with Cr/Cu source-drain electrodes was the highest performance, around 9.95 cm2/Vs. After annealing at 200°C for one hour in air, it increased by 51.42 cm<sup>2</sup>/Vs. It has found that the sputtered film had many sulfur defects according to the TFT simulation and XPS study. To compensate for the defects, we have tried oxidization by the How-Wire method. As a result, the mobility increased to 62.73 cm<sup>2</sup>/Vs. The effect of oxygen introduction has been investigated by first-principles calculations [2]. Furthermore, it was found that the sulfur defects exist between the layers must be reduced in order to reduce the off-current. It was annealed at 200°C for 1 hour in a metal-sealed container containing S powder. We have succeeded in suppressing the off-current less than 10<sup>-10</sup> A.<br/><br/>[1] Adam T. Neal, Ruth Pachter, and Shin Mou, Appl. Phys. Lett. 110, 193103 2017,<br/>[2] M. Chhowalla, H. S. Shin, G. Eda, L-J. Li, K. P. Loh and H.Zhang<br/>nature chemistry 5. 263-275 (2013)