Direct measurement of key exciton properties: Energy, dynamics, and spatial distribution of the wave function
Journal article, 2021
Excitons, Coulomb-bound electron–hole pairs, are the fundamental excitations governing the optoelectronic properties of semiconductors. Although optical signatures of excitons have been studied extensively, experimental access to the excitonic wave function itself has been elusive. Using multidimensional photoemission spectroscopy, we present a momentum-, energy-, and time-resolved perspective on excitons in the layered semiconductor WSe2. By tuning the excitation wavelength, we determine the energy–momentum signature of bright exciton formation and its difference from conventional single-particle excited states. The multidimensional data allow to retrieve fundamental exciton properties like the binding energy and the exciton–lattice coupling and to reconstruct the real-space excitonic distribution function via Fourier transform. All quantities are in excellent agreement with microscopic calculations. Our approach provides a full characterization of the exciton properties and is applicable to bright and dark excitons in semiconducting materials, heterostructures, and devices. Key points: The full life cycle of excitons is recorded with time- and angle-resolved photoemission spectroscopy. The real-space distribution of the excitonic wave function is visualized. Direct measurement of the exciton-phonon interaction.
ultrafast dynamics
semiconductors
exciton physics
many-body physics
quasi-particle interactions
condensed matter physics
time-resolved photoemission spectroscopy
Author
Shuo Dong
Max Planck Society
Michele Puppin
Max Planck Society
Swiss Federal Institute of Technology in Lausanne (EPFL)
Tommaso Pincelli
Max Planck Society
Samuel Beaulieu
Max Planck Society
Dominik Christiansen
Technische Universität Berlin
Hannes Hübener
Max Planck Society
Christopher W. Nicholson
Max Planck Society
University of Fribourg
Rui Patrick Xian
Max Planck Society
Maciej Dendzik
Royal Institute of Technology (KTH)
Max Planck Society
Yunpei Deng
Max Planck Society
Paul Scherrer Institut
Yoav William Windsor
Max Planck Society
M. Selig
Technische Universität Berlin
Ermin Malic
Chalmers, Physics, Condensed Matter and Materials Theory
Angel Rubio
Max Planck Society
A. Knorr
Technische Universität Berlin
Martin Wolf
Max Planck Society
Laurenz Rettig
Max Planck Society
Ralph Ernstorfer
Max Planck Society
Natural Sciences
26986248 (eISSN)
Vol. 1 1 e10010Subject Categories
Atom and Molecular Physics and Optics
Condensed Matter Physics
DOI
10.1002/ntls.10010