Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 4: 2D semiconductors and van der Waals heterostructures I (joint session HL/DS/O)

DS 4.6: Talk

Monday, March 16, 2020, 10:45–11:00, POT 81

2D Semiconductors in moving and standing phonon fields — •Tobias M. Petzak, Emeline D. S. Nysten, and Hubert J. Krenner — Lehrstuhl für Experimentalphysik 1, Institut für Physik, Universität Augsburg, Universitätstr. 1, 86159 Augsburg, Germany

In this work, we prepare two-dimensional layers of transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2 or WSe2 via micromechanical exfoliation and transfer them into the propagation path of a Surface Acoustic Wave (SAW) directly on a LiNbO3 substrate via viscoelastic stamping. The electric field of the SAW couples to the electron system of the monolayer semiconductors and, thus, we gain insight into the dynamics of photogenerated charges in the sample in a non-invasive, completely contact-free, way.

Additionally, we coupled WSe2 monolayers to the phononic modes of a high quality factor SAW resonator. This resonator-based spectroscopy increases the sensitivity of our technique. In spectrally resolved experiments using the resonator we are able to resolve the absorption edge of the 2D semiconductor which is in agreement with photoluminescence data. The latter results mark the first major step toward highly sensitive SAW spectroscopy employing SAW resonators.