Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 57: 2D Materials beyond Graphene: TMDCs, Slicene and Relatives
O 57.7: Talk
Wednesday, March 18, 2015, 16:45–17:00, MA 005
Charge carrier trapping and electron-phonon coupling in MoS2 revealed by µ-Raman spectroscopy — Bastian Miller1,2, Eric Parzinger1,2, Alexander Holleitner1,2, and •Ursula Wurstbauer1,2 — 1Walter Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4a, 85748 Garching — 2Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 München, Germany
Two-dimensional layered van-der Waals materials are of increasing interest for fundamental research as well as device applications in the areas of electronics, spin- and valleytronics, optoelectronics, and sensing. We utilize power and gate voltage dependent non-resonant and resonant µ-Raman spectroscopy on dual-gate field-effect transistor devices to study doping effects, e-ph coupling and the impact of trap states in mono-, bi- and few layer MoS2. In non-resonant Raman measurements we observe a strong power- and gate voltage dependence of zone-center Raman modes with contrasting behavior for mono- and bilayer MoS2. Under resonant excitation, a rich scattering spectra with signatures of multistep scattering processes are observable pointing towards contribution from phonon-phonon and electron-phonon interaction. The origin of the different modes, their dependence on the exciting light energy and evolution with number of layers will be discussed. We acknowledge the financial support by the DFG excellence cluster Nanosystems Initiative Munich (NIM).