Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Ultrafast Electron Dynamics I: Surfaces and Interfaces (joint session O/MA)
O 8.3: Talk
Monday, March 16, 2020, 11:00–11:15, TRE Phy
Interfacial carrier and phonon dynamics in nanostructured metal/2D-semiconductor plasmonic heterostructures — •Tommaso Pincelli1, Thomas Vasileiadis1, Shuo Dong1, Samuel Beaulieu1, Maciej Dendzik1, Daniela Zahn1, Sang-Eun Lee1, Hélène Seiler1, Yinpeng Qi1, Patrick Xian1, Julian Maklar1, Emerson Coy2, Niclas Müller3, Yu Okamura3, Stephanie Reich3, Martin Wolf1, Laurenz Rettig1, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut der MPG, Berlin, Germany — 2NanoBioMedical Centre, Adam Mickiewicz University, Poznan, Poland — 3Freie Universität Berlin, Berlin, Germany
Noble metal nanostructures enhance light absorption in semiconductors to produce plasmons, whose decay couples strongly with the generation of hot carriers and non-equilibrium phonons. We combine the use of time and angle-resolved photoemission spectroscopy and femtosecond electron diffraction to investigate both charge carrier and phonon dynamics in a plasmonic metal/semiconductor heterostructure.
We grow epitaxial Au nanoislands on single-crystalline bulk WSe2. The presence of Au nanostructures causes a shortening of the Σ-exciton lifetime and an accelerated lattice heating of WSe2, which indicate interfacial charge transfer. Furthermore, we observe a non-equilibrium phonon distribution in WSe2 with sub-bandgap optical pumping, demonstrating increased sensitivity of the semiconductor to near infrared frequencies. The corresponding energy transfer scales nonlinearly with the incident laser fluence, owing to plasmonically-enhanced phonon excitation.