Confocal optical microscopy and tip-enhanced optical microscopy are applied to characterize the defect distributions in chemical vapor deposition-grown WS2 monolayer triangles qualitatively and quantitatively. The presence of defects in individual monolayer WS2 triangles is revealed with diffraction-limited spatial resolution in their photoluminescence (PL) images, from which the inhomogeneous defect density distribution is calculated, showing an inverse relationship to the PL intensity. The defect-related surface-enhanced Raman spectroscopy (SERS) effect is investigated by depositing a thin copper phthalocyanine layer (5 nm) as the probe molecule on the monolayer WS2 triangles surface. Higher SERS enhancement effects are observed at the defect-rich areas. Furthermore, tip-enhanced optical measurements are performed, which can reveal morphologically defected areas invisible in the confocal optical measurements. Furthermore, the area with high defect density appears brighter than the low-defected area in the tip-enhanced optical measurements, which are different from the observation in the confocal optical measurements. The underlying reasons are attributed to the near-field enhancement of the defect exciton emission induced by the optically excited tip and to an improved coupling efficiency between the tip-generated near-field with the altered dipole moment orientation at the local defect.
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Inhomogeneous defect distribution of triangular WS2 monolayer revealed by surface-enhanced and tip-enhanced Raman and photoluminescence spectroscopy
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21 January 2022
Research Article|
January 18 2022
Inhomogeneous defect distribution of triangular WS2 monolayer revealed by surface-enhanced and tip-enhanced Raman and photoluminescence spectroscopy
Special Collection:
Chemical Imaging
Peng Miao;
Peng Miao
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
2
Harbin Institute of Technology
, Harbin, People’s Republic of China
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Yu-Ting Chen;
Yu-Ting Chen
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Lin Pan
;
Lin Pan
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
4
Laboratoire Lumière, nanomatériaux et nanotechnologies – L2n, Université de Technologie de Troyes & CNRS EMR 7004
, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France
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Anke Horneber;
Anke Horneber
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Katharina Greulich;
Katharina Greulich
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Thomas Chassé;
Thomas Chassé
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Heiko Peisert
;
Heiko Peisert
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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Pierre-Michel Adam;
Pierre-Michel Adam
4
Laboratoire Lumière, nanomatériaux et nanotechnologies – L2n, Université de Technologie de Troyes & CNRS EMR 7004
, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France
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Ping Xu;
Ping Xu
2
Harbin Institute of Technology
, Harbin, People’s Republic of China
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Alfred Meixner
;
Alfred Meixner
a)
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
a)Authors to whom correspondence should be addressed: alfred.meixner@uni-tuebingen.de and dai.zhang@uni-tuebingen.de
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Dai Zhang
Dai Zhang
a)
1
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen
, Auf der Morgenstelle 18, 72076 Tübingen, Germany
3
Center for Light-Matter-Interaction, Sensors and Analytics (LISA+), Eberhard Karls University of Tübingen
, Auf der Morgenstelle 15, 72076 Tübingen, Germany
a)Authors to whom correspondence should be addressed: alfred.meixner@uni-tuebingen.de and dai.zhang@uni-tuebingen.de
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a)Authors to whom correspondence should be addressed: alfred.meixner@uni-tuebingen.de and dai.zhang@uni-tuebingen.de
Note: This paper is part of the JCP Special Topic on Chemical Imaging.
J. Chem. Phys. 156, 034702 (2022)
Article history
Received:
November 10 2021
Accepted:
December 22 2021
Citation
Peng Miao, Yu-Ting Chen, Lin Pan, Anke Horneber, Katharina Greulich, Thomas Chassé, Heiko Peisert, Pierre-Michel Adam, Ping Xu, Alfred Meixner, Dai Zhang; Inhomogeneous defect distribution of triangular WS2 monolayer revealed by surface-enhanced and tip-enhanced Raman and photoluminescence spectroscopy. J. Chem. Phys. 21 January 2022; 156 (3): 034702. https://doi.org/10.1063/5.0078113
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