Bulk-suppressed and surface-sensitive Raman scattering by transferable plasmonic membranes with irregular slot-shaped nanopores
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Date
2024-06-19
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Journal Article
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yes
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Abstract
Raman spectroscopy enables the non-destructive characterization of chemical composition, crystallinity, defects, or strain in countless materials. However, the Raman response of surfaces or thin films is often weak and obscured by dominant bulk signals. Here we overcome this limitation by placing a transferable porous gold membrane, (PAuM) on the surface of interest. Slot-shaped nanopores in the membrane act as plasmonic antennas and enhance the Raman response of the surface or thin film underneath. Simultaneously, the PAuM suppresses the penetration of the excitation laser into the bulk, efficiently blocking its Raman signal. Using graphene as a model surface, we show that this method increases the surface-to-bulk Raman signal ratio by three orders of magnitude. We find that 90% of the Raman enhancement occurs within the top 2.5 nm of the material, demonstrating truly surface-sensitive Raman scattering. To validate our approach, we quantify the strain in a 12.5 nm thin Silicon film and analyze the surface of a LaNiO3 thin film. We observe a Raman mode splitting for the LaNiO3 surface-layer, which is spectroscopic evidence that the surface structure differs from the bulk. These results validate that PAuM gives direct access to Raman signatures of thin films and surfaces.
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published
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Volume
15
Pages / Article No.
5236
Publisher
Nature
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03944 - Novotny, Lukas / Novotny, Lukas
03918 - Fiebig, Manfred / Fiebig, Manfred
09482 - Vermant, Jan / Vermant, Jan
Notes
Funding
188414 - Multifunctional oxide electronics using natural ferroelectric superlattices (SNF)
SEED-16 17-1 - Nanoscale slot antennas for gas sensing (ETHZ)
192362 - Antenna-coupled Optoelectronics (SNF)
SEED-16 17-1 - Nanoscale slot antennas for gas sensing (ETHZ)
192362 - Antenna-coupled Optoelectronics (SNF)