Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 57: Focus Session: Many-body effects in two-dimensional materials
O 57.1: Hauptvortrag
Mittwoch, 9. März 2016, 09:30–10:00, H16
Probing bandgap renormalization, excitonic effects, and interlayer coupling in 2D transition metal dichalcogenide semiconductors — •Miguel M. Ugeda1, Aaron Bradley1, Sufei Shi1, Felipe H. Jornada1, Yi Zhang2,3, Diana Qiu1, Wei Ruan1, Sebastian Wickenburg1, Alexander Riss1, Jiong Lu1, Sung-Kwan Mo2, Zahid Hussain2, Zhi-Xun Shen3, Feng Wang1, Steven G. Louie1, and Michael F. Crommie1 — 1Department of Physics, University of California, Berkeley, CA 94720, USA. — 2Advanced Light Source, Lawrence Berkeley National Lab., Berkeley, CA 94720, USA. — 3Stanford Institute for Materials and Energy Sciences, Menlo Park, CA 94025, USA.
Reduced screening in 2D metal dichalcogenides (TMDs) has been predicted to result in dramatically enhanced Coulomb interactions that should cause giant bandgap renormalization and excitonic effects. Here we present direct experimental observation of extraordinarily high exciton binding energy and band structure renormalization in a single-layer of semiconducting TMD[1]. We have determined the binding energy of correlated electron-hole excitations in monolayer MoSe2 grown via molecular beam epitaxy on bilayer graphene by using a combination of scanning tunneling spectroscopy and photoluminescence spectroscopy. We have also studied the role of interlayer coupling and layer-dependent carrier screening on the electronic structure[2] of few layer MoSe2. We find that the electronic quasiparticle bandgap decreases by nearly 1 eV when going from one layer to three. [1]Nature Materials 13, 1091 (2014). [2]Nano Letters 15, 2594 (2015).