Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: Poster: 2D Materials beyond Graphene: TMDCs, Silicene and Relatives
O 48.19: Poster
Dienstag, 13. März 2018, 18:15–20:30, Poster A
Hot carrier dynamics in semiconducting transition-metal dichalcogenides – valley-polarized excitation in bulk 2H-MoS2 and monolayer WS2/Au(111) — •Hauke Beyer1, Gerald Rohde1, Antonija Grubisic Cabo2, Ankatrin Stange1, Luca Bignardi3, Daniel Lizzit3, Paolo Lacovig3, Silvano Lizzit3, Kai Rossnagel1, Philip Hofmann2, and Michael Bauer1 — 1Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany — 2Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark — 3Elettra Sincrotrone Trieste, S.S. 14 Km 163.5, 34149 Trieste, Italy
Time- and angle-resolved photoelectron spectroscopy (trARPES) is employed to study the valley-selective excitation and near-surface dynamics of carriers at K and K′ in semiconducting transition-metal dichalcogenides (TMDC). Upon photoexcitation with circularly polarized laser pulses (λ ≈ 600 nm), circular dichroism can be observed in excited-state intensity as well as dynamics. The poster will present and compare experimental results of bulk 2H-MoS2 and monolayer WS2/Au(111). In the latter case, we observe a significantly enhanced dichroism of the excitation intensity in comparison to the bulk sample, which we attribute to the lack of mirror domains of the WS2 sample. Furthermore, a dependence of the population dynamics on the polarization state of the excitation laser pulse is observed only for 2H-MoS2. This difference is associated with K to K′ intervalley scattering processes affecting the carrier dynamics in bulk TMDC samples but being absent in the case of monolayer WS2/Au(111).