Dresden 2020 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 14: TEM-based Nanoanalysis and Microstructure of thin films (joint session KFM/CPP)
KFM 14.5: Vortrag
Donnerstag, 19. März 2020, 15:40–16:00, HSZ 301
Uncloaking structural information of ultra-thin oxide films by surface enhanced Raman spectroscopy — •Mads C. Weber1, Sebastian Heeg2, Roman Wyss3, Martin Sarott1, Morgan Trassin1, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich — 2Department of Information Technology and Electrical Engineering, ETH Zurich — 3Department of Mechanical and Process Engineering, ETH Zurich
Strained oxide thin films are a source for properties nonexistent in bulk form such as ferrelectricity in SrTiO3 or altered conductivity in nickelates. These physical properties result commonly from subtle structural distortions. Unfortunately, subtle distortions and specifically oxygen displacements are chronically difficult to probe hindering an in-depth understanding of the phenomena. Here, we introduce surface enhanced Raman spectroscopy (SERS) – a technique so far restricted to molecules and carbon-nanostructures – to scrutinize the structure of oxide thin films. A porous gold membrane deposited on the sample acts as antenna and amplifies the Raman signal of the outer layers only. Using this method, we set the Raman spectra of our model thin film LaNiO3 apart from the substrate giving the important structural insight. Beside information on the strain state of LaNiO3, we identify an ultra-thin surface layer structurally different from the rest of the film. Such a surface layer was so far only theoretically predicted, however, never observed. In general, we anticipate that the introduction of SERS to reign of complex oxides films will help to understand the link between novel physical phenomena and structural distortions.