Probing the Role of Interlayer Coupling and Coulomb Interactions on Electronic Structure in Few-Layer MoSe2 Nanostructures
A. J. Bradley, M. M. Ugeda, F. H. da Jornada, D. Y. Qiu, W. Ruan, Y. Zhang, S. Wickenburg, A. Riss, J. Lu, S.-K. Mo, Z. Hussain, Z.-X. Shen, S. G. Louie, M. F. Crommie
Department of Physics, University of California, Berkeley, CA 94720, U. S. A.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U. S. A.
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U. S. A.
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, U. S. A.
Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, U. S. A.
Kavli Energy NanoSciences Institute, University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, U. S. A.
Institut für Angewandte Physik,
Technische Universität Wien, 1040 Wien, Austria
Nano Lett. 15 (2015) 2594-2599
Despite the weak nature of interlayer forces in transition metal dichalcogenide (TMD) materials,
their properties are highly dependent on the number of layers in the few-layer two-dimensional (2D) limit.
Here, we present a combined scanning tunneling microscopy/spectroscopy and GW theoretical study
of the electronic structure of high quality single- and few-layer MoSe2 grown on bilayer graphene.
We find that the electronic (quasiparticle) bandgap, a fundamental parameter for transport and optical phenomena,
decreases by nearly one electronvolt when going from one layer to three due to interlayer coupling and screening effects.
Our results paint a clear picture of the evolution of the electronic wave function hybridization in the valleys
of both the valence and conduction bands as the number of layers is changed.
This demonstrates the importance of layer number and electron-electron interactions on van der Waals heterostructures
and helps to clarify how their electronic properties might be tuned in future 2D nanodevices.
Corresponding author: Miguel M. Ugeda
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