Achieving Adsorbate-Free Monolayered MoS₂ Field Effect Transistors by Controlled Surface Gas Treatment

Monolayered transition metal dichalcogenides (TMDCs) possess a highly sensitive nature to external elements, particularly adsorbed molecules on the surface such as H 2 O or O 2 molecules, due to their atomically thin structure. In this sense, it is important to develop a strategy to obtain a pristine surface of 2D TMDCs for the successful and reliable fabrication of a device with their originally intended functions. Here, we suggest a facile strategy of surface treatment to effectively eliminate the influence of adsorbed molecules in the electrical performance of the monolayered MoS 2 FETs via surface treatment using highly reactive H 2 S gas at room temperature. We demonstrated increased carrier concentration of absorbate-free MoS 2 using various spectroscopy and electrical measurements. The H 2 S-treated MoS 2 FETs showed a 171% increase in on-current level and reduced hysteresis window compared to pristine MoS 2 FETs. Moreover, the H 2 S-treated MoS 2 FETs exhibit increased field effect mobility. Additionally, we verified that the clean interface of MoS 2 is preserved through dry passivation of MoS 2 FETs. This unique room temperature surface treatment strategy allows the development of highly conductive MoS 2 FETs with a clean surface by a very simple process.