Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 67: Graphene-like Materials: Silicene, MoS2 and Relatives (HL jointly with DY, MA, O, TT)

O 67.4: Talk

Thursday, April 3, 2014, 10:45–11:00, POT 081

Carrier- and valley dynamics of singlelayer MoS₂ — •Gerd Plechinger¹, John Mann², Christian Schüller¹, Ludwig Bartels², and Tobias Korn¹ — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany — ²Chemistry, Physics, and Materials Science and Engineering, University of California, CA 92521 Riverside, USA

Consisting of an only 0.7 nm thin S-Mo-S sheet and offering a direct bandgap at the K-points in the Brillouin zone, singlelayer MoS₂ represents a promising semiconductor material for flexible and transparent optoelectronic applications. By means of chemical vapor deposition (CVD), large-area films (several mm²) of singlelayer MoS₂ can be produced. These were characterised by photoluminescence and Raman spectroscopy. In order to investigate the carrier dynamics, we performed pump-probe measurements in the spectral range of the optical transitions in singelayer MoS₂. Helicity-resolved PL measurements have demonstrated an efficient valley polarisation of the K⁺ or K⁻ valley at near-resonant excitation. We probe these valley dynamics with Kerr spectroscopy and find a biexponential decay of the valley polarisation with decay times of a few tens of ps and a few hundreds of ps at low temperatures.