Imaging Nanoscale Inhomogeneities and Edge Delamination in As-Grown MoS2 Using Tip-Enhanced Photoluminescence

Abstract

Methods for nanoscale material characterization are in ever-increasing demand, especially those that can provide a broader range of information at once. Near-field techniques based on combinations of scanning probe microscopy (SPM) and Raman or photoluminescence (PL) spectroscopy (tip-enhanced Raman spectroscopy [TERS] and/or tip-enhanced photoluminescence [TEPL]) are, thanks to their capabilities and fast development, strong candidates for becoming widespread across the scientific community as SPM and Raman microscopy did only a decade or two ago. Herein, a gap-less TEPL study is performed directly on as-grown MoS2 monolayer samples without any pretreatment or transfer, i.e., without the utilization of plasmonic substrate. Thanks to a mapping resolution as low as a few tens of nanometers, homogeneous layer interiors from defective edge fronts in the grown monolayers can be distinguished. With the aid of additional high-resolution SPM modes, like local surface potential and capacitance measurements, together with nanomechanical mapping, a combination of defects and a lack of substrate doping is suggested as being responsible for the observed PL behavior in the partially delaminated MoS2 layers. In contrast, mechanically exfoliated flakes show topography- and contamination-related heterogeneities in the whole flake area.

References in corpus (11)

• Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor Deposition
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• Local strain engineering in atomically thin MoS2
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• Hierarchy of Graphene Wrinkles Induced by Thermal Strain Engineering
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• The edge delamination of monolayer transition metal dichalcogenides

Cited by in corpus (4)

• Fingerprints of the Strong Interaction between Monolayer MoS2 and Gold
• Probing the Local Dielectric Function by Near Field Optical Microscopy Operating in the Visible Spectral Range
• Nano-optical investigation of grain boundaries, strain and edges in CVD grown MoS${}_2$ monolayers
• Symmetric Domain Segmentation in WS2 Flakes: Correlating spatially resolved photoluminescence, conductance with valley polarization