Berlin 2018 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 12: Ultrafast Electron and spin dynamics at interfaces II
O 12.3: Vortrag
Montag, 12. März 2018, 15:30–15:45, MA 005
Ultrafast charge transfer in epitaxial WS2/graphene van der Waals heterostructures — •Isabella Gierz1, Sven Aeschlimann1, Mariana Chavez-Cervantes1, Razvan Krause1, Antonio Rossi2, and Camilla Coletti2 — 1Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany — 2Center for Nanotechnology @ NEST, Istituto Italiano di Tecnologia, Pisa, Italy
Reduced screening together with confinement results in strong electron-electron interactions in two dimensional solids. Since the discovery of graphene, a semi-metal with linear band structure, many other layered materials have been reduced to monolayer thickness. One example are monolayer group VI transition metal dichalcogenides, direct band gap semiconductors with broken inversion symmetry that, in the presence of strong spin-orbit coupling, produces a sizable spin splitting of the band structure up to several hundreds of meV. Stacking different two-dimensional materials to from van der Waals heterostructures offers the possibility to tune their electronic properties and to produce new functionalities. We use femtosecond laser pulses to photo-dope epitaxial WS2/graphene heterostructures [1,2] and investigate the resulting carrier dynamics with time- and angle-resolved photoemission spectroscopy (tr-ARPES). We find evidence for ultrafast charge transfer between the layers that rapidly fills the photo-induced holes in the valence band of WS2.
[1] Rossi et al., 2D Mater. 3, 031013 (2016)
[2] Forti et al., Nanoscale 9, 16412 (2017)