Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 38: 2D materials: Chalcogenides II (joint session HL/DS)
HL 38.5: Talk
Thursday, March 15, 2018, 10:30–10:45, A 151
Exciton-phonon coupling in mono- and bilayer MoTe2 — •Sophia Helmrich1, Robert Schneider2, Alexander W. Achtstein1, Ashish Arora2, Bastian Herzog1, Steffen Michaelis de Vasconcellos2, Mirco Kolarczik1, Oliver Schöps1, Rudolf Bratschitsch2, Ulrike Woggon1, and Nina Owschimikow1 — 1Institut für Optik und Atomare Physik, Technische Universität Berlin, Germany — 2Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Germany
We investigate excitonic transitions of mechanically exfoliated monolayer and bilayer molybdenum ditelluride (MoTe2) by temperature-dependent photoluminescence spectroscopy. Based on identical scaling of the excitonic optical bandgap and the integrated area of the emission with temperature we conclude that ML and BL MoTe2 have similar band alignment and excitonic behavior. Our experiments show that for identical excitation laser power the bilayer yields twice the intensity as the monolayer unlike for other transition metal dichalcogenides. From the emission lines we extract key parameters for exciton-phonon coupling processes demonstrating an unusually small coupling with acoustical phonons of γLA = (28 ± 4) µeV K−1 and (14 ± 4) µeV K−1 for ML and BL MoTe2, respectively, where the interactions with longitudinal optical phonons of ΓLO= (40.1 ± 5.6) meV ((86.4± 12.6) meV) for ML (BL) MoTe2 are comparable to values of other TMDs. These observations make MoTe2 an attractive and robust material with a large luminescence yield for applications in the technically relevant near-infrared region.