Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: 2D Materials I: Growth and Properties of Transition Metal Dichalcogenides, Phase Transitions

O 35.2: Vortrag

Dienstag, 2. April 2019, 14:15–14:30, H14

Charge-transfer across the MoSe₂/WSe₂ interface studied with second-harmonic imaging microscopy — •Jonas E. Zimmermann, Ulrich Höfer, and Gerson Mette — Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, 35032 Marburg

2D transition metal dichalcogenides (TMDC) have been in the center of attention since the discovery of extraordinary luminescence for MoS₂. TMDC heterostructures in particular gain more and more popularity due to their possible applications in optoelectronics. As the efficiency of such devices is expected to depend strongly on the charge transfer across the heterointerface, it is of crucial importance to investigate the charge-carrier dynamics on a fundamental level.
Here we present results of our second-harmonic (SH) imaging microscopy setup for time-resolved studies on interfaces of 2D materials. This technique enables us to quantify the crystal orientation via polarization dependent measurements and at the same time provides access to the charge-carrier dynamics by femtosecond pump-probe experiments. Measurements performed on MoS₂ monolayers show a strong pump-induced change in the SH response which corresponds well to the fingerprint of exciton generation reported for this material. In contrast, experiments on a MoSe₂/WSe₂ heterostructure reveal a delayed filling as well as an enhanced lifetime of the temporal signature. These findings suggest the generation of interlayer excitons in the heterostructure.