Signatures Of Defect-Localized Charged Excitons In The Photoluminescence Of Monolayer Molybdenum Disulfide

We study spatial photoluminescence characteristics of neutral and charged excitons across extended mono-layer MoS2 synthesized by chemical vapor deposition. Using two-dimensional hyperspectral photoluminescence mapping at cryogenic temperatures we identify regions with increased emission from charged excitons associated with both spin-orbit split valence subbands. Such regions are attributed to unintentional doping at defect sites with excess charge that bind neutral excitons to form defect-pinned trions. Our findings imply comparable timescales for the formation, relaxation, and radiative decay of B trions, and add defect-localized A and B trions to the realm of photoexcited quasiparticles in layered semiconductors.