SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Ultrafast Electron Dynamics at Surface and Interfaces III
O 34.3: Vortrag
Dienstag, 28. März 2023, 11:00–11:15, TRE Phy
Influence of the substrate dielectric permittivity on ultrafast quasiparticles dynamics in WS2 monolayers — •Subhadra Mohapatra1,2, Lukas Gierster1,2, Stefano Calati1,2, Nicholas Michael Olsen3, Quiyang Li3, Xiaoyang Zhu3, and Julia Stähler1,2 — 1Humboldt-Universität zu Berlin, Institut für Chemie — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Abt. Physikalische Chemie, Berlin, Germany — 3Columbia University
In our recent fluence-and photon energy-dependent studies [1,2] of quasiparticle dynamics in WS2 monolayers on fused silica (FS) and Si-SiO2 substrates, we observed that excitonic screening reduces the binding energy of the excitons, however the role of screening due to substrates and the quantitative nature of dynamic screening due to excitons remained inconclusive. On further investigation of such fluence-dependent quasiparticle dynamics studies using a higher dielectric permittivity of a sapphire substrate, we found that scattering rates, relaxation time constants, and band gap renormalization are not influenced by the dielectric permittivity. On the contrary, the dynamic screening parameter of the excitons is approximately two times higher in FS than Sapphire and Bohr radius is approximately 2.5 % higher in sapphire than for FS, which must be a direct consequence of the increased dielectric permittivity likely leading to more delocalized excitons.
References:
[1] Calati et al. PCCP 23(39) (2021).
[2] Calati et al. arXiv:2204.02125 (2022).