Surface wettability modification of CVD-grown MoS$_{2}$ by oxygen plasma treatment

Two dimensional MoS$_{2}$ FET (field-effect transistor) has been emerging as an outstanding semiconductor device platform for bio-sensor. MoS$_{2}$ FET has not only a good stability in electrolyte and pH changes but also tunability for surface engineering, which provides a good opportunity for bio-sensor platforms. Recently many studies have been reported on electronic and optical properties of MoS$_{2}$ while less effort has been made to investigate the surface wettability of CVD-grown MoS$_{2}$ and modification of atomically layered MoS$_{2}$ surface property. In this study, we investigated the surface energy of MoS$_{2}$ with various layer thickness (1L, 2L and 3L) and effect of O$_{2}$ plasma treatment. We synthesized mono- to tri-layer of large-area MoS$_{2}$ with CVD (chemical vapor deposition) method and conducted surface characterization of MoS$_{2}$ supported on SiO$_{2}$/Si substrate using atomic force microscopy and contact angle measurement. We show tunable wetting properties of plasma-engineered MoS$_{2}$.