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Fabrication of tunable plasmonic substrates using a table-top gold coater and a hot plate, their optical characterization, and surface enhanced Raman activity
Ankit Arora,
Published in American Institute of Physics Inc.
2015
Volume: 118
   
Issue: 15
Abstract
We present a simple scalable technique for repeatable fabrication of large area (cm2) electromagnetic hot spots using tunable Localized Surface Plasmon Resonance (LSPR) substrates and their k-space microscopic imaging characterization. The substrates were fabricated simply using a low vacuum air plasma scanning electron microscope gold coater and annealing using a hot plate. The measured permittivity profile and optical transmission characteristics of such substrates showed large changes before and after annealing, with clear changes in the occurrence and position of the LSPR in the visible spectrum. Furthermore, the LSPR wavelength of these substrates was tuned from 537nm to 630nm using cyclic deposition and annealing. It was observed that every anneal step could be used to blue shift the resonance, while a deposition step could be used to red shift the resonance, thus giving rise to a wide tunability. We also present the k-space images of the substrates using narrowband fluorescence leakage radiation microscopy and broadband polarization microscopy. The enhanced scattering in these substrates was clearly imaged in the k-space, and the color content in the broadband k-space images correlates well with the spectral characteristics of these substrates that can be used in commercial quality testing without a spectrometer. The optical characteristics of the substrates were attributed to the morphology evolution verified using scanning probe microscopy. A single particle model based simulation was used to evaluate the optical response. The substrates were then tested for surface enhanced Raman spectroscopy (SERS) activity using control experiments involving Rhodamine 6G dye in PMMA matrix of different concentrations with analyte volumes of approximately 200pl and analytical enhancements of >3�104 (net enhancement >1.8�107) were obtained. The limit of detection was ∼10-8M in low volume (∼200pl) analyte, reaching the regime of few molecule detection. To establish the relevance of the substrates for bio-sensing, surface functionalization using thioglycolic acid was measured using SERS. � 2015 AIP Publishing LLC.
About the journal
JournalData powered by TypesetJournal of Applied Physics
PublisherData powered by TypesetAmerican Institute of Physics Inc.
ISSN00218979
Open AccessNo
Concepts (21)
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    Annealing
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    Deposition
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    Fabrication
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    Gold
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    Light transmission
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    Plasmons
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    Raman spectroscopy
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    Resonance
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    Scanning electron microscopy
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    Scanning probe microscopy
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    Spectrometers
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    Surface plasmon resonance
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    Localized surface plasmon resonance
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    Optical characteristics
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    Optical characterization
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    POLARIZATION MICROSCOPY
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    Spectral characteristics
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    Surface enhanced raman spectroscopy
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    Surface functionalization
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    Transmission characteristics
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    Substrates