First-principles study of vacancy defects at interfaces between monolayer MoS2 and Au.

Abstract

The performance of MoS2 based devices is closely related to the quality and defect morphology of the monolayer MoS2 deposited on metal. First-principles calculations were performed to investigate the vacancy effects of Au–mMoS2 contact. Four possible S-vacancy and a Mo-vacancy were considered in our calculations. Energetic studies show that S-vacancies are easier to form than Mo-vacancy in Au–mMoS2 contact, while S-vacancy (hollow site at interface, VS4) has the lowest formation energy under Mo-rich environments. Electron and charge redistribution analysis of defective Au–mMoS2 contact indicate that the lower contact resistance and higher electron injection efficiency of defective Au–MoS2 contact than perfect ones. Notably, the S-vacancy at top layer showed better electronic performance than that at bottom layer of monolayer MoS2 in the contact. High quality n-type Au–mMoS2 contact can therefore be expected through defect engineering.