Evidence of indirect gap in monolayer WSe₂.

ABSTRACT: Monolayer transition metal dichalcogenides, such as MoS₂ and WSe₂, have been known as direct gap semiconductors and emerged as new optically active materials for novel device applications. Here we reexamine their direct gap properties by investigating the strain effects on the photoluminescence of monolayer MoS₂ and WSe₂. Instead of applying stress, we investigate the strain effects by imaging the direct exciton populations in monolayer WSe₂-MoS₂ and MoSe₂-WSe₂ lateral heterojunctions with inherent strain inhomogeneity. We find that unstrained monolayer WSe₂ is actually an indirect gap material, as manifested in the observed photoluminescence intensity-energy correlation, from which the diffe

SUBMITTER: Hsu WT 

PROVIDER: S-EPMC5640683 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature