Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 9: Plasmonics and Nanooptics I: Local Probes and Raman (joint session O/CPP)
O 9.4: Talk
Monday, March 16, 2020, 11:15–11:30, WIL A317
Spatial and spectral mode mapping of a Sb2S3 nanodot by broadband interferometric homodyne scanning near-field spectroscopy — Jinxin Zhan1, Wei Wang2, Jens Brauer1, Lukas Schmidt-Mende2, Christoph Lienau1, and •Petra Groß1 — 1Carl von Ossietzky Universität, Oldenburg, Germany — 2University of Konstanz, Konstanz, Germany
We present and demonstrate a novel approach towards broad-bandwidth scattering-type near-field scanning optical spectroscopy based on homodyne mixing and on rapid acquisition of spectra facilitating tip-modulated spectroscopy. We aim at a fast and spectrally resolved near-field measurement of plasmonic and dielectric nanostructures. The weak, broad-bandwidth near field is amplified above the background by homodyne mixing using a Michelson interferometer, and spectral interferograms over a >150 nm bandwidth are recorded. For rapid acquisition of complete spectra, we use a monochromator and a line camera with 210-kHz readout rate. The near-field spectra obtained after demodulation show supreme background suppression.
We apply this new method to the characterization of Sb2S3 semiconductor nanodots fabricated by electron beam lithography. Sb2S3 recently became attractive as photovoltaic material, and patterning the surface of a thin film with nanodots of the same material is a strategy to achieve light trapping. Here, we present spatially and spectrally resolved measurements of waveguide-like modes that are excited by below-bandgap illumination. These constitute a practical mechanism for improved below-bandgap absorption in Sb2S3 thin film solar cells.