Spectrally Tunable, Large Raman Enhancement from Nonradiative Energy Transfer in the van der Waals Heterostructure

Dandu, M and Watanabe, K and Taniguchi, T and Sood, AK and Majumdar, K (2020) Spectrally Tunable, Large Raman Enhancement from Nonradiative Energy Transfer in the van der Waals Heterostructure. In: ACS Photonics, 7 (2). pp. 519-527.

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Abstract

Raman enhancement techniques are essential for fundamental studies in light-matter interactions and find widespread application in microelectronics, biochemical sensing, and clinical diagnosis. Two-dimensional (2D) materials and their van der Waals heterostructures (vdWHs) are emerging rapidly as potential platforms for Raman enhancement. Here, we experimentally demonstrate a new technique of Raman enhancement driven by nonradiative energy transfer (NRET), achieving a 10-fold enhancement in the Raman intensity in a vertical vdWH comprising of a monolayer transition metal dichalcogenide (1L-TMD) placed on a multilayer SnSe2. Consequently, several weak Raman peaks become visible, which are otherwise imperceptible. We also show a strong modulation of the enhancement factor by tuning the spectral overlap between the 1L-TMD and SnSe2 through temperature variation, and the results are in remarkable agreement with a Raman polarizability model capturing the effect of NRET. The observed NRET-driven Raman enhancement is a novel mechanism that has not been experimentally demonstrated thus far and is distinct from conventional surface (SERS), tip (TERS), or interference enhanced Raman scattering (IERS) mechanisms that are driven solely by charge transfer or electric field enhancement. The mechanism can also be used in synergy with plasmonic nanostructures to achieve additional selectivity and sensitivity beyond hot spot engineering for applications like molecular detection using 2D/molecular hybrids. Our results open new avenues for engineering Raman enhancement techniques coupling the advantages of uniform enhancement accessible across a wide junction area in vertical vdWHs.

Item Type:	Journal Article
Publication:	ACS Photonics
Publisher:	AMER CHEMICAL SOC
Additional Information:	The copyright of this article belongs to AMER CHEMICAL SOC
Keywords:	Charge transfer; Diagnosis; Electric fields; Energy transfer; Layered semiconductors; Microelectronics; Molybdenum compounds; Selenium compounds; Transition metals; Tungsten compounds; Van der Waals forces, MoS2; Nonradiative energy transfer; Raman enhancement; SnSe2; Van der waals, Tin compounds
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering Division of Physical & Mathematical Sciences > Physics
Date Deposited:	17 Jun 2020 09:44
Last Modified:	17 Jun 2020 09:44
URI:	http://eprints.iisc.ac.in/id/eprint/64819

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