The doping mechanism and electrical performance of polyethylenimine‐doped MoS­2 transistor

Abstract

Seongin Hong et al. (article no. 1600262) have investigated the polyethylenimine (PEI) doping mechanism and its effect on the electrical and optical properties of multilayer MoS2 field effect transistors (FETs). Density functional theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) measurement confirm that the PEI molecules were successfully doped and formed Mo–N bonds on the MoS2 channel, generating new energy states near the valence band. The strong n-doping changed the threshold voltage as well as the Schottky barrier width attributed to the induced interfacial dipoles. Therefore, the ON-current of the doped MoS2 FETs was improved in comparison with the pristine FETs. Furthermore, the PEI doping also enhanced the photoresponsivity of the MoS2 FETs from 0.14 A/W to 4.41 A/W. This study suggests that PEI molecular doping could be widely applicable to two-dimensional materials in order to improve the electrical and optical properties of respective devices.