Largely Enhanced Mobility of MoS 2 Field-Effect Transistors by Optimizing O 2 -Plasma Treatment on MoS 2

2-D layered MoS2 is considered as a promising candidate for novel nanoelectronic devices in recent years. However, a large number of structural defects in MoS2 have been widely reported, which will greatly degrade the electrical performance of MoS2 devices. In this work, it is demonstrated that the structural defects in MoS2 can be repaired by a reasonable-power O2-plasma treatment, e.g., a 30-W O2-plasma treatment on MoS2 results in an enhanced carrier mobility of 69.82 cm2/Vs, which is 2.5 times higher than that of the untreated devices, a reduced subthreshold swing of 131.27 mV/dec, and a high ON/OFF current ratio of $3.18\times 10^{{6}}$ . These are attributed to the fact that the suitable-power O2-plasma treatment can effectively repair the structural defects in MoS2 and reduce the scattering centers, improving the electrical performance of MoS2 FETs. However, a high-power O2 plasma will generate high-energy oxygen ions to bombard the MoS2, introducing more new defects and deteriorating the electrical performance of MoS2 FETs.