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Influence of fractal and lacunar characteristic of a nanostructured substrate on SERS enhancement

Risović, Dubravko; Gebavi, Hrvoje; Ivanda, Mile (2021) Influence of fractal and lacunar characteristic of a nanostructured substrate on SERS enhancement. Applied Surface Science, 537 . ISSN 0169-4332

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Nanostructured materials play a significant role in numerous advanced and diversified applications many of which exploit their optical properties. Among these are nanostructured substrates for surface-enhanced Raman scattering (SERS). The objective of our study was to contribute to understanding of topological aspects influencing and underlying SERS on nanostructured substrates. To that purpose we fabricated Ag-decorated Si-nanowires (SiNWs) substrates with different fractal and lacunar characteristics. We demonstrated that fractal dimension and lacunarity have a profound influence on SERS enhancement. We discussed the involved interplay between long-range properties of nanostructured substrate, namely its fractal topology, and short-range local features on a nanometer scale related to the distribution of inter-wire gaps (i.e. lacunarity) which strongly affect the local field enhancement, altogether precipitating in significant increase of SERS. Explanation of a strong correlation found to exist between fractal dimension D, lacunarity and SERS enhancement and the observed abrupt increase of SERS at D ≈ 2.54 are provided within the framework of the percolation theory. For a percolated fractal structure a strong enhancement depends on the excitation wavelength resonantly matching the heterogeneity sizes of inter nanowire gaps as characterized with a high lacunarity determining the distribution of localized optical excitations i.e. hot spots.

Item Type: Article
Uncontrolled Keywords: SERS ; Silicon nanowires ; Fractal nanostructure ; Lacunarity ; SERS substrate
Subjects: NATURAL SCIENCES > Physics > Atomic and Molecular Physics
Divisions: Center of Excellence for Advanced Materials and Sensing Devices
Project titleProject leaderProject codeProject type
Potpora vrhunskim istraživanjima Centra izvrsnosti za napredne materijale i senzoreUNSPECIFIEDKK.
Depositing User: Hrvoje Gebavi
Date Deposited: 02 Dec 2020 12:44
DOI: 10.1016/j.apsusc.2020.147915

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