Raman spectroscopy of silicon with nanostructured surface
Magdaléna Kadlečíková (Slovak University of Technology)
Ľubomír Vančo (Slovak University of Technology)
Juraj Breza (Slovak University of Technology)
Miroslav Mikolášek (Slovak University of Technology)
Kristína Hušeková (Slovak Academy of Sciences)
Karol Fröhlich (Slovak Academy of Sciences)
Paul Procel (TU Delft - Photovoltaic Materials and Devices)
Miro Zeman (TU Delft - Electrical Sustainable Energy)
Olindo Isabella (TU Delft - Photovoltaic Materials and Devices)
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Abstract
We compared the morphology and Raman response of nanoscale shaped surfaces of Si substrates versus monocrystalline Si. Samples were structured by reactive ion etching, and four of them were covered by a RuO2-IrO2 layer. Raman bands, centred at approx. 520 cm–1, belonging to samples processed by etching the Si surface have intensities higher by approximately one order of magnitude than those of reference non-etched samples. For nanostructured samples, the rise in the Raman signal was 12–14 ×, which is in agreement with the model of the electric field at the tips of Si due to their geometry. This phenomenon is related to the high absorption of excitation radiation. Nanostructured surfaces of samples containing a layer of RuO2-IrO2 give rise to the phenomenon of surface enhancement of the Raman response most likely due to the charge transfer at the interface between silicon and conductive oxides. The nanostructured surface of Si without a metal layer behaves as a SERS substrate and detects the analytes at a low concentration.