Strong photoluminescence enhancement of MoS2 monolayer via low-power Ar/O2 plasma treatment

MoS2 has attracted considerable attention given its excellent optoelectronic properties arising from the quantum size effect. Intrinsic defects, especially sulfur vacancies, are common in the as-prepared MoS2 monolayer, significantly restricting monolayer photoluminescence. An efficient method is reported in this paper to passivate the sulfur vacancies of the MoS2 monolayer through low-power-density Ar/O2 plasma treatment. The photoluminescence spectrum shows a dramatic enhancement of ∼150 times, attributed to the transition from trion to exciton and the inhibition of a non-radiative recombination of photo-excitons. Measurement results indicate the formation of Mo-O bonds in the plasma-treated MoS2 monolayer without an obvious etching effect. The strong photoluminescence intensity of the monolayer may have promising applications in optoelectronic devices.