Achieving Adsorbate-Free Monolayered MoS<sub>2</sub> Field Effect Transistors by Controlled Surface Gas Treatment

Abstract

Monolayered transition metal dichalcogenides (TMDCs) possess a highly sensitive nature to external elements, particularly adsorbed molecules on the surface such as H2O 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 MoS2 FETs via surface treatment using highly reactive H2S gas at room temperature. We demonstrated increased carrier concentration of absorbate-free MoS2 using various spectroscopy and electrical measurements. The H2S-treated MoS2 FETs showed a 171% increase in on-current level and reduced hysteresis window compared to pristine MoS2 FETs. Moreover, the H2S-treated MoS2 FETs exhibit increased field effect mobility. Additionally, we verified that the clean interface of MoS2 is preserved through dry passivation of MoS2 FETs. This unique room temperature surface treatment strategy allows the development of highly conductive MoS2 FETs with a clean surface by a very simple process.