Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 68: Metal-Semiconductor Hybrids
HL 68.9: Vortrag
Donnerstag, 10. März 2016, 12:15–12:30, H10
Interaction of Porous Silicon Photonic Crystals and Plasmonic Nanostructures for Applications in Surface-Enhanced Raman Spectroscopy — •Martin Fränzl, Stefan Moras, and Dietrich R.T. Zahn — Semiconductor Physics, Technische Universität Chemnitz, Germany
We fabricated porous silicon photonic crystals by electrochemical etching of p-doped silicon in hydrogen fluoride solution. By applying a periodic etching current we obtain a periodic change of the porosity and thus a periodic variation of the effective refractive index. This represents a photonic crystal in one dimension and results in a very high reflectance in the photonic band gap. The plasmonic structures were fabricated using nanosphere lithography leading to metallic nanostructure arrays. These ordered structures show a collective plasmonic resonance with a high absorbance and a very low transmission. We combined these structures by using the porous silicon photonic crystal as substrate for the nanosphere lithography and designed both structures so that the plasmonic resonance is located in the center of the photonic band gap. The properties of the structures were measured using spectroscopic ellipsometry and simulated using effective medium theories and finite-element methods. The high reflectance of the photonic crystal and the absorbance at the plasmonic resonance results in a strong confinement and enhancement of electric fields at the interface. We performed surface-enhanced Raman spectroscopy (SERS) measurements by depositing a thin layer of CoPc on top of the composite structure and report a giant SERS enhancement factor in the order of 105.