title: Near-field spectral mapping of individual exciton complexes of monolayer WS2correlated with local defects and charge population.
abstract: Exciton transitions are mostly responsible for the optical properties of transition metal dichalcogenide monolayers (1L-TMDs). Extensive studies of optical and structural characterization indicated that the presence of local structural defects and charge population critically influence the exciton emissions of 1L-TMDs. However, due to large variations of sample and experimental conditions, the exact mechanism of the exciton emission influenced by local structural defects and charge population is not clearly understood. In this work by using near-field scanning optical imaging and spectroscopy, we directly visualized spatially- and spectrally-resolved emission profiles of excitons, trions and defect bound excitons in CVD-grown monolayer tungsten disulfide (1L-WS2) with ∼70 nm spatial resolution. We found that exciton emission is spatially uniform while emission of trions and defect bound excitons was strongly modulated by the presence of structural features such as defects and wrinkles. We also visually observe a strong correlation between local charge accumulation and the trion formation upon increased photo-excitation.
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 440-746, Republic of Korea and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Lee
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 440-746, Republic of Korea and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Seok Joon
authors.initials: SJ
authors.lastname: Yun
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 440-746, Republic of Korea and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Youngbum
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Min Su
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Gang Hee
authors.initials: GH
authors.lastname: Han
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Sood
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 440-746, Republic of Korea and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea. j.kim@skku.edu.
authors.forename: Jeongyong
authors.identifier: http://orcid.org/0000-0003-4679-0370
authors.initials: J
authors.lastname: Kim