Raman Signal Enhancement Tunable by Gold-Covered Porous Silicon Films with Different Morphology
Svetlana N. Agafilushkina,
Olga Žukovskaja,
Sergey A. Dyakov,
Karina Weber,
Vladimir Sivakov,
Jürgen Popp,
Dana Cialla-May,
Liubov A. Osminkina
Affiliations
Svetlana N. Agafilushkina
Physics Department, Lomonosov Moscow State University, 119991 Moscow, Russia
Olga Žukovskaja
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07745 Jena, Germany
Sergey A. Dyakov
Skolkovo Institute of Science and Technology, Nobel Street 3, 143025 Moscow, Russia
Karina Weber
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07745 Jena, Germany
Vladimir Sivakov
Leibniz Institute of Photonic Technology, Member of the Leibniz Research Allicance, Leibniz Health Technologies, Albert-Einstein-Straße 9, 07745 Jena, Germany
Jürgen Popp
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07745 Jena, Germany
Dana Cialla-May
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07745 Jena, Germany
Liubov A. Osminkina
Physics Department, Lomonosov Moscow State University, 119991 Moscow, Russia
The ease of fabrication, large surface area, tunable pore size and morphology as well surface modification capabilities of a porous silicon (PSi) layer make it widely used for sensoric applications. The pore size of a PSi layer can be an important parameter when used as a matrix for creating surface-enhanced Raman scattering (SERS) surfaces. Here, we evaluated the SERS activity of PSi with pores ranging in size from meso to macro, the surface of which was coated with gold nanoparticles (Au NPs). We found that different pore diameters in the PSi layers provide different morphology of the gold coating, from an almost monolayer to 50 nm distance between nanoparticles. Methylene blue (MB) and 4-mercaptopyridine (4-MPy) were used to describe the SERS activity of obtained Au/PSi surfaces. The best Raman signal enhancement was shown when the internal diameter of torus-shaped Au NPs is around 35 nm. To understand the role of plasmonic resonances in the observed SERS spectrum, we performed electromagnetic simulations of Raman scattering intensity as a function of the internal diameter. The results of these simulations are consistent with the obtained experimental data.
