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나노 구조 물리 연구단
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Heterogeneous modulation of exciton emission in triangular WS2 monolayers by chemical treatment

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Title
Heterogeneous modulation of exciton emission in triangular WS2 monolayers by chemical treatment
Author(s)
Krishna P. Dhakal; Shrawan Roy; Seok Joon Yun; Ganesh Ghimire; Changwon Seo; Jeongyong Kim
Publication Date
2017-07
Journal
Journal of Materials Chemistry C, v.5, no.27, pp.6820 - 6827
Publisher
ROYAL SOC CHEMISTRY
Abstract
Chemical treatments were recently shown to be very effective in enhancing the exciton emission of monolayer transition metal dichalcogenides (1L-TMDs) by suppressing the exciton quenching caused by structural defects. However, the effects of these chemical treatments varied greatly depending on the synthesis method and the type of 1L-TMD; therefore, the exact origin of the emission enhancement is still elusive. Here we report the spatially heterogeneous effects of bis(trifluoromethane) sulfonimide (TFSI) and benzyl viologen (BV) treatment on the optical properties of triangular 1L-WS2 grown by chemical vapor deposition (CVD). Nanoscale photoluminescence (PL) and Raman spectral maps showed that TFSI had a minimal effect on the inner region of the triangular WS2 grain, whereas the PL of the edge region was enhanced up to 25 times; further, BV reduced the PL, also more strikingly in the edge region. Systematic variation of the spectral weights among neutral excitons, trions, and bi-excitons indicated that p-doping and n-doping with TFSI and BV, respectively, occurred in both the inner and edge regions; however, the PL enhancement was attributed mainly to the reduction of structural defects caused by TFSI treatment. Our observation of the spatially heterogeneous effects of chemical treatment suggests that the inner and edge regions of CVD-grown 1L-WS2 are populated with different types of structural defects and helps in clarifying the mechanism by which chemical treatment enhances the optical properties of 1L-TMDs. This journal is ©The Royal Society of Chemistry 2017
URI
https://pr.ibs.re.kr/handle/8788114/3836
ISSN
2050-7526
Appears in Collections:
Center for Integrated Nanostructure Physics(나노구조물리 연구단) > Journal Papers (저널논문)
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