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Proceedings Paper

Sub-nanometer-gap tip-enhanced nanoimaging of few-layer MoS2 (Conference Presentation)
Author(s): Dmitri V. Voronine

Paper Abstract

Two-dimensional (2D) materials beyond graphene such as transition metal dichalcogenides (TMDs) have unique mechanical, optical and electronic properties with promising applications in flexible devices, catalysis and sensing. Optical imaging of TMDs using photoluminescence and Raman spectroscopy can reveal the effects of structure, strain, doping, defects, edge states, grain boundaries and surface functionalization. However, Raman signals are inherently weak and so far have been limited in spatial resolution in TMDs to a few hundred nanometres which is much larger than the intrinsic scale of these effects. Here we overcome the diffraction limit by using resonant tip-enhanced Raman scattering (TERS) of few-layer MoS2, and obtain nanoscale optical images with ~ 20 nm spatial resolution. This becomes possible due to electric field enhancement in an optimized subnanometre-gap resonant tip-substrate configuration. We investigate the limits of signal enhancement by varying the tip-sample gap with sub-Angstrom precision and observe a quantum quenching behavior, as well as a Schottky-Ohmic transition, for subnanometre gaps, which enable surface mapping based on this new contrast mechanism. This quantum regime of plasmonic gap-mode enhancement with a few nanometre thick MoS2 junction may be used for designing new quantum optoelectronic devices and sensors.

Paper Details

Date Published: 3 November 2016
PDF: 1 pages
Proc. SPIE 9932, Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices IX, 99320B (3 November 2016); doi: 10.1117/12.2238870
Show Author Affiliations
Dmitri V. Voronine, Texas A&M Univ. (United States)

Published in SPIE Proceedings Vol. 9932:
Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices IX
Manijeh Razeghi; Maziar Ghazinejad; Can Bayram; Jae Su Yu, Editor(s)

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