Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.9: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Strain induced optical effects of WS₂ monolayers — •Marcel Ney, Aswin Asaithambi, Lukas Madauß, Günther Prinz, Marika Schleberger, and Axel Lorke — Faculty of Physics and CENIDE, University Duisburg-Essen, Germany

Two-dimensional transition metal dichalcogenide (TMD) monolayers interact efficiently with visible light due to the direct bandgap nature at K-point in momentum space. The result of the quantum confinement effects in two dimensions is a strong electron-hole Coulomb interaction, leading to a large exciton binding energy, which makes this material very promising for optoelectronic device fabrication.

We will present photoluminescence- (PL) and Raman spectroscopy results of WS₂ monolayers grown on a standard Si/SiO₂ substrate via a chemical vapor deposition (CVD) process.

In PL investigations, we observed a redshift of the excitonic wavelength between the center and the edge of a triangular WS₂ monolayer. These redshifting recombination energies could indicate strain within the monolayer. Therefore complementary Raman spectroscopy measurements were performed, which results support the assumption of a strain induced excitonic redshift. The maximum relative tensile strain was calculated to 1.2%, applying a relation between strain and Raman shift [1].

The influence of strain on the optical properties of WS₂ monolayers at temperatures ranging from 295K to 77K and for different excitation powers will be discussed and compared with results from literature.

[1] F. Wang et al., 2D Mater. 4, 015007 (2016)