Fabrication of novel plasmonics-active substrates

Anuj Dhawan; Michael Gerhold; Yan Du; Veena Misra; Tuan Vo-Dinh

doi:10.1117/12.809887

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18 February 2009 Fabrication of novel plasmonics-active substrates

Anuj Dhawan, Michael Gerhold, Yan Du, Veena Misra, Tuan Vo-Dinh

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Proceedings Volume 7205, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics II; 72050S (2009) https://doi.org/10.1117/12.809887
Event: SPIE MOEMS-MEMS: Micro- and Nanofabrication, 2009, San Jose, California, United States

Abstract

This paper describes methodologies for fabricating of highly efficient plasmonics-active SERS substrates - having metallic nanowire structures with pointed geometries and sub-5 nm gap between the metallic nanowires enabling concentration of high EM fields in these regions - on a wafer-scale by a reproducible process that is compatible with large-scale development of these substrates. Excitation of surface plasmons in these nanowire structures leads to substantial enhancement in the Raman scattering signal obtained from molecules lying in the vicinity of the nanostructure surface. The methodologies employed included metallic coating of silicon nanowires fabricated by employing deep UV lithography as well as controlled growth of silicon germanium on silicon nanostructures to form diamond-shaped nanowire structures followed by metallic coating. These SERS substrates were employed for detecting chemical and biological molecules of interest. In order to characterize the SERS substrates developed in this work, we obtained SERS signals from molecules such as p-mercaptobenzoic acid (pMBA) and cresyl fast violet (CFV) attached to or adsorbed on the metal-coated SERS substrates. It was observed that both gold-coated triangular shaped nanowire substrates as well as gold-coated diamond shaped nanowire substrates provided very high SERS signals for the nanowires having sub-15 nm gaps and that the SERS signal depends on the closest spacing between the metal-coated silicon and silicon germanium nanowires. SERS substrates developed by the different processes were also employed for detection of biological molecules such as DPA (Dipicolinic Acid), an excellent marker for spores of bacteria such as Anthrax.

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Anuj Dhawan, Michael Gerhold, Yan Du, Veena Misra, and Tuan Vo-Dinh "Fabrication of novel plasmonics-active substrates", Proc. SPIE 7205, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics II, 72050S (18 February 2009); https://doi.org/10.1117/12.809887

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