Inhomogeneous defect distribution of triangular WS 2 monolayer revealed by surface-enhanced and tip-enhanced Raman and photoluminescence spectroscopy.

Autor: Miao P; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Chen YT; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Pan L; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Horneber A; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Greulich K; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Chassé T; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Peisert H; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Adam PM; Laboratoire Lumière, nanomatériaux et nanotechnologies - L2n, Université de Technologie de Troyes & CNRS EMR 7004, 12 Rue Marie Curie, CS42060, 10004 Troyes Cedex, France., Xu P; Harbin Institute of Technology, Harbin, People's Republic of China., Meixner A; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany., Zhang D; Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Jazyk: angličtina
Zdroj: The Journal of chemical physics [J Chem Phys] 2022 Jan 21; Vol. 156 (3), pp. 034702.
DOI: 10.1063/5.0078113
Abstrakt: Confocal optical microscopy and tip-enhanced optical microscopy are applied to characterize the defect distributions in chemical vapor deposition-grown WS 2 monolayer triangles qualitatively and quantitatively. The presence of defects in individual monolayer WS 2 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 WS 2 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.
Databáze: MEDLINE
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