Characteristics of Cl-doped MoS2 field-effect transistors

Abstract

MoS2 is among the two-dimensional (2D) transition metal dichalcogenides (TMD) and has been studied as a potential semiconductor material for various devices. To increase the performance of MoS2-based devices, contact engineering of metal to TMD materials has recently become an area of focus. The doping method is one way to reduce resistance, and molecular doping is a suitable doping method for MoS2 with a very thin layer structure. We demonstrate controllable molecular doping on MoS2 transistors using 1,2 dichloroethane (DCE) solution. Chloride molecules contained within the DCE solution act as an n-type dopant and increase the carrier density. The doping effects were confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy, and current-voltage characteristics. We observed that the threshold voltages shifted toward the negative direction, implying electron doping of MoS2 after Cl-doping. Additionally, the field-effect mobility and the carrier densities were enhanced from 11.9 cm2·V−1·s−1 to 72.8 cm2·V−1·s−1 and from 3.62 × 1011 cm-2 to 1.37 × 1012 cm-2, respectively, by increasing the molar concentration of 1,2-dichloroethane solution to 12.6 M.