Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 49: Focus Session: Many-body effects in two-dimensional materials (Joint session of HL and O, organized by HL)

HL 49.1: 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 Zhang^2,3, 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).