Unsicherheits- und Vertrauensaspekte bei der Integration von VGI und raum-zeitlicher Trajektorien zum Verstehen von Tierverhalten
- AG Keim (Data Analysis and Visualization)
|(2020): Dielectric Nanoantennas for Strain Engineering in Atomically Thin Two-Dimensional Semiconductors ACS Photonics. ACS Publications. 2020, 7(9), pp. 2413-2422. eISSN 2330-4022. Available under: doi: 10.1021/acsphotonics.0c00294
Atomically thin two-dimensional semiconducting transition metal dichalcogenides (TMDs) can withstand large levels of strain before their irreversible damage occurs. This unique property offers a promising route for control of the optical and electronic properties of TMDs, for instance, by depositing them on nanostructured surfaces, where position-dependent strain can be produced on the nanoscale. Here, we demonstrate strain-induced modifications of the optical properties of mono- and bilayer TMD WSe2 placed on photonic nanoantennas made from gallium phosphide (GaP). Photoluminescence (PL) from the strained areas of the TMD layer is enhanced owing to the efficient coupling with the confined optical mode of the nanoantenna. Thus, by following the shift of the PL peak, we deduce the changes in the strain in WSe2 deposited on the nanoantennas of different radii. In agreement with the presented theory, strain up to ≈1.4% is observed for WSe2 monolayers. We also estimate that >3% strain is achieved in bilayers, accompanied by the emergence of a direct bandgap in this normally indirect-bandgap semiconductor. At cryogenic temperatures, we find evidence of the exciton confinement in the most strained nanoscale parts of the WSe2 layers, as also predicted by our theoretical model. Our results of direct relevance for both dielectric and plasmonic nanoantennas, show that strain in atomically thin semiconductors can be used as an additional parameter for engineering light–matter interaction in nanophotonic devices.
|(2018): Theory of strain-induced confinement in transition metal dichalcogenide monolayers Physical Review B. 2018, 97(19), 195454. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.97.195454
Recent experimental studies of out-of-plane straining geometries of transition metal dichalchogenide (TMD) monolayers have demonstrated sufficient band-gap renormalization for device application, such as single-photon emitters. Here, a simple continuum-mechanical plate-theory approach is used to estimate the topography of TMD monolayers layered atop nanopillar arrays. From such geometries, the induced conduction-band potential and band-gap renormalization are given, demonstrating a curvature of the potential that is independent of the height of the deforming nanopillar. Additionally, with a semiclassical WKB approximation, the expected escape rate of electrons in the strain potential may be calculated as a function of the height of the deforming nanopillar. This approach is in accordance with experiment, supporting recent findings suggesting that increasing nanopillar height decreases the linewidth of the single-photon emitters observed at the tip of the pillar and predicting the shift in photon energy with nanopillar height for systems with consistent topography.
|07.06.2019 – 06.06.2022