Ultrafast Band Structure Control of a Two-Dimensional Heterostructure.
The electronic structure of two-dimensional (2D) semiconductors can be significantly altered by screening effects, either from free charge carriers in the material or by environmental screening from the surrounding medium. The physical properties of 2D semiconductors placed in a heterostructure with other 2D materials are therefore governed by a complex interplay of both intra- and interlayer interactions. Here, using time- and angle-resolved photoemission, we are able to isolate both the layer-resolved band structure and, more importantly, the transient band structure evolution of a model 2D heterostructure formed of a single layer of MoS2 on graphene. Our results reveal a pronounced renormalization of the quasiparticle gap of the MoS2 layer. Following optical excitation, the band gap is reduced by up to ∼400 meV on femtosecond time scales due to a persistence of strong electronic interactions despite the environmental screening by the n-doped graphene. This points to a large degree of tunability of both the electronic structure and the electron dynamics for 2D semiconductors embedded in a van der Waals-bonded heterostructure.
Advanced Light Source, E. O. Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Søren
S
Ulstrup
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Antonija Grubišić
AG
Čabo
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Jill A
JA
Miwa
SUPA, School of Physics and Astronomy, University of St. Andrews , St. Andrews KY16 9AJ, United Kingdom.
Jonathon M
JM
Riley
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Signe S
SS
Grønborg
Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne, Switzerland.
Jens C
JC
Johannsen
Central Laser Facility, STFC Rutherford Appleton Laboratory , Harwell OX11 0QX, United Kingdom.
Cephise
C
Cacho
Central Laser Facility, STFC Rutherford Appleton Laboratory , Harwell OX11 0QX, United Kingdom.
Oliver
O
Alexander
Central Laser Facility, STFC Rutherford Appleton Laboratory , Harwell OX11 0QX, United Kingdom.
Richard T
RT
Chapman
Central Laser Facility, STFC Rutherford Appleton Laboratory , Harwell OX11 0QX, United Kingdom.
Emma
E
Springate
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Marco
M
Bianchi
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Maciej
M
Dendzik
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Jeppe V
JV
Lauritsen
SUPA, School of Physics and Astronomy, University of St. Andrews , St. Andrews KY16 9AJ, United Kingdom.
Phil D C
PD
King
Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University , 8000 Aarhus C, Denmark.
Philip
P
Hofmann
2D material heterostructures; MoS2; band gap renormalization; graphene; transition metal dichalcogenides; ultrafast time- and angle-resolved photoemission