Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 3: 2D semiconductors and van der Waals heterostructures I (joint session HL/DS/O)
O 3.12: Talk
Monday, March 16, 2020, 12:45–13:00, POT 81
Defect-related photoluminescence of WS2 monolayers — •Marcel Ney, Aswin Asaithambi, Lukas Madauß, Marika Schleberger, Axel Lorke, and Günther Prinz — 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 band gap nature at the 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 devices.
We will present low-temperature photoluminescence-spectroscopy (PL) measurements, which show the influence of laser-irradiation with different excitation powers on WS2 monolayers grown on a standard Si/SiO2 substrate via a chemical vapor deposition (CVD) process.
In the PL investigations, we observed a defect-related emission D1, which can be assigned to adsorbate-decorated defect complexes [1]. The nature of this defect-related state investigated by laser-power-dependent measurements, will be presented in this contribution. During a laser excitation cycle, a laser-activated emission with a higher energy than the defect-related emission D1, occurs. Furthermore, another defect-related emission D2 was observed. Due to the annealing properties after laser-irradiation we identify this emission as a monosulfur vacancy decorated with physisorbed adsorbates [2].
[1] Z. He et al., ACS Nano 10, 5847 (2016)
[2] V. Carozo et al., Science Advances 3, e1602813 (2017)