Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 59: Poster Wednesday: Plasmonics and Nanooptics 2

O 59.3: Poster

Mittwoch, 7. September 2022, 18:00–20:00, P4

Near-field optical investigation of bandgap effects in SnTe — •Christian Justus, Konstantin G. Wirth, Dario Siebenkotten, Lukas Conrads, Sophia Wahl, Matthias Wuttig, and Thomas Taubner — I. Institute of Physics (IA), RWTH Aachen University

Phase change materials (PCMs) are prime candidates for non-volatile memory solutions[1]. Storage mediums with high memory density require a method for determining material properties with nanometer precision. One such tool to investigate the optical properties of nano-structures is scattering-type scanning near-field optical microscopy (s-SNOM). Thus far, bandgap effects in semiconductors have eluded experimental observation in s-SNOM. Specifically metavalently bonded materials may exhibit a bandgap shift by over a factor of three in reduced dimensions, such as in the case of Tin Telluride (SnTe) with a shift from 0.2 to 0.7 eV[2]. The primary goal of this work is to use s-SNOM to spectoscopically characterize bandgap effects in SnTe thin films. We find good agreement between Fourier-transform infrared spectroscopy (FTIR) and s-SNOM measurements over a spectral range spanning 0.3 to 0.9 eV and are able to identify a bandgap contribution to the spectral s-SNOM data. Our results may help to get a deeper insight into confinement effects on the optical properties of nano-scale PCM structures, such as PCM memory cells, and may provide a valuable tool for the analysis and characterization of PCM memory devices with high storage density.