Aeschlimann, Sven and Rossi, Antonio and Chavez-Cervantes, Mariana and Krause, Razvan and Arnoldi, Benito and Stadtmueller, Benjamin and Aeschlimann, Martin and Forti, Stiven and Fabbri, Filippo and Coletti, Camilla and Gierz, Isabella (2020) Direct evidence for efficient ultrafast charge separation in epitaxial WS2/graphene heterostructures. SCIENCE ADVANCES, 6 (20): eaay0761. ISSN 2375-2548,
Full text not available from this repository. (Request a copy)Abstract
We use time- and angle-resolved photoemission spectroscopy (tr-ARPES) to investigate ultrafast charge transfer in an epitaxial heterostructure made of monolayer WS2 and graphene. This heterostructure combines the benefits of a direct-gap semiconductor with strong spin-orbit coupling and strong light-matter interaction with those of a semimetal hosting massless carriers with extremely high mobility and long spin lifetimes. We find that, after photoexcitation at resonance to the A-exciton in WS2, the photoexcited holes rapidly transfer into the graphene layer while the photoexcited electrons remain in the WS2 layer. The resulting charge-separated transient state is found to have a lifetime of similar to 1 ps. We attribute our findings to differences in scattering phase space caused by the relative alignment of WS2 and graphene bands as revealed by high-resolution ARPES. In combination with spin-selective optical excitation, the investigated WS2/graphene heterostructure might provide a platform for efficient optical spin injection into graphene.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | VALLEY POLARIZATION; TUNGSTEN DISULFIDE; GRAPHENE; MOS2; FIELD; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 26 Mar 2021 07:40 |
| Last Modified: | 26 Mar 2021 07:40 |
| URI: | https://pred.uni-regensburg.de/id/eprint/44654 |
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