SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 69: Poster Session V: Poster to Mini-Symposium: Infrared nano-optics III

O 69.1: Poster

Mittwoch, 3. März 2021, 10:30–12:30, P

Nano-scale analysis of Phase Change Material thin films using a Scattering-type Scanning Near-field Optical Microscope (s-SNOM) — •Oxana Maurer, Julian Barnett, Konstantin Wirth, Lisa Schäfer, Matthias Wuttig, and Thomas Taubner — Institute of Physics (IA), RWTH Aachen

Phase Change Materials (PCMs) possess two or more different states with a distinct contrast in optical and electrical properties. The states can be switched in a reversible and non-volatile manner, leading to applications in optical and electrical data storage, but also in photonics and thermoelectrics. PCMs exhibit a bonding mechanism referred to as metavalent bonding (MVB)[1], which is characterised by a competition between electron localisation and delocalisation. Based on theoretical calculations, indications of MVB seem to persist down to the 2D limit [2], e.g GeTe shows PCM properties down to a few bilayers and its band gap is increasing for decreasing film thickness. To verify this, the optical near-field response of ultrathin PCM films are investigated with a scattering-type Scanning Near-field Optical Microscope (s-SNOM). Until now, a fundamental understanding of band gap effects on the s-SNOM contrast is lacking. Therefore, our measurements are combined with theoretical modelling to gain insight into the s-SNOM contrast changes introduced by band gaps.

[1] B. J. Kooi, M. Wuttig (2020) Adv. Mater. 32, 1908302

[2] I. Ronneberger, et al. (2020) Adv. Mater. 30, 2001033