Improving the electrical performance of monolayer top-gated MoS₂transistors by post bis(trifluoromethane) sulfonamide treatment

Due to the large surface to volume ratio of two-dimensional (2D) materials, the electrical performance of MoS2 is very sensitive to extrinsic ambient conditions. Post treatments are favorable to improve or recover the electrical performance of MoS2. In this work, the influence of post forming gas annealing (FGA) and bis(trifluoromethane) sulfonamide (TFSI) treatment on the electrical performance of monolayer top-gated MoS2 transistors is investigated. A negative shift of threshold voltage and an improvement in electron mobility are observed for both the post FGA and TFSI treatment. However, post TFSI treatment is more effective than the post FGA treatment in improving the electron mobility and gate controllability. Linear transmission-line-model measurement results indicate that the post FGA treatment is preferable in reducing the contact resistance, while post TFSI treatment is more effective in reducing the sheet resistance of MoS2. Raman and x-ray photoelectron spectroscopy reveal that water desorbs from MoS2 after the FGA and TFSI treatment and S vacancies are introduced into MoS2 after FGA. The results show that post TFSI treatment can be a simple and effective approach to improve the electrical property of MoS2 and may be used for other S-containing 2D transition metal dichalcogenides.