Simple, Large-Scale Fabrication of Uniform Raman-Enhancing Substrate with Enhancement Saturation
Abstract
It is well-known that gold nanoparticle (AuNP) clusters generate strong surface-enhanced Raman scattering (SERS). In order to produce spatially uniform Raman-enhancing substrates at a large scale, we synthesized vertically perforated three-dimensional (3D) AuNP stacks. The 3D stacks were fabricated by first hydrothermally synthesizing ZnO nanowires perpendicular to silicon wafers followed by repetitively performing liquid-phase deposition of AuNPs on the tops and side surfaces of the nanowires. During the deposition process, the nanowires were shown to gradually dissolve away, leaving hollow vestiges or perforations surrounded by stacks of AuNPs. Simulation studies and experimental measurements reveal these nanoscale perforations serve as light paths that allow the excitation light to excite deeper regions of the 3D stacks for stronger overall Raman emission. Combined with properly sized nanoparticles, this feature maximizes and saturates the Raman enhancement at 1-pM sensitivity across the entire wafer-scale substrate, and the saturation improves the wafer-scale uniformity by a factor of 6 when compared to nanoparticle layers deposited directly on a silicon wafer substrate. Using the 3D-stacked substrates, quantitative sensing of adenine molecules yielded concentrations measurements within 10% of the known value. Understanding the enhancing mechanisms and engineering the 3D stacks have opened a new method of harnessing the intense SERS observed in nanoparticle clusters and realize practical SERS substrates with significantly improved uniformity suitable for quantitative chemical sensing.
Additional Information
© 2017 American Chemical Society. Received: March 6, 2017; Accepted: April 28, 2017; Published: April 28, 2017. The research was funded by Samsung Grand Research Opportunity and Heritage Medical Research Institute Inaugural Principle Investigator Program. The authors also thank Professor Inkyu Park for helpful discussion on the AuNP synthesis. Author Contributions: The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. The authors declare no competing financial interest.Attached Files
Accepted Version - acsami_2E7b03239.pdf
Supplemental Material - am7b03239_si_001.pdf
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Additional details
- Eprint ID
- 77094
- DOI
- 10.1021/acsami.7b03239
- Resolver ID
- CaltechAUTHORS:20170501-090908942
- Samsung Grand Research Opportunity
- Heritage Medical Research Institute
- Created
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2017-05-01Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Heritage Medical Research Institute