Photoluminescence of monolayer MoS2 on LaAlO3 and SrTiO3 substrates

Abstract

In an atomically thin-film/dielectric-substrate heterostructure, the elemental physical properties of the atomically thin-film are influenced by the interaction between the thin-film and the substrate. In this article, utilizing monolayer MoS₂ on LaAlO₃ and SrTiO₃ substrates, as well as SiO₂ and Gel-film as reference substrates similar to previously reported work [Nano Res, 2014, 7, 561], we systematically investigate the substrate effect on the photoluminescence of monolayer MoS₂. We observed significantly substrate-dependant photoluminescence of monolayer MoS₂, originating from substrate-to-film charge transfer. We found that SiO₂ substrate introduces the most charge doping while SrTiO₃ introduces less charge transfer. Through the selection of desired substrate, we are able to induce different amounts of charge into the monolayer MoS₂, which consequently modifies the neutral exciton and charged exciton (trion) emissions. Finally, we proposed a band-diagram model to elucidate the relation between charge transfer and the substrate Fermi level and work function. Our work demonstrates that the substrate charge transfer exerts a strong influence on the monolayer MoS₂ photoluminescence property, which should be considered during device design and application. The work also provides a possible route to modify the thin-film photoluminescence property via substrate engineering for future device design.