Regensburg 2019 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
SYTS: Symposium Interaction Effects and Correlations in twodimensional Systems - New Challenges for Theory
SYTS 1: Interaction effects and correlations in twodimensional systems - New challenges for theory
SYTS 1.3: Hauptvortrag
Mittwoch, 3. April 2019, 16:00–16:30, H1
Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors — •Alexander Steinhoff1, Matthias Florian1, Malte Rösner1,2,3, Gunnar Schönhoff1,2, Tim O. Wehling1,2, and Frank Jahnke1 — 1Institute for Theoretical Physics, University of Bremen, Germany — 2Bremen Center for Computational Materials Science, University of Bremen, Germany — 3Present address: Center for Computational Quantum Physics, Flatiron Institute, New York
When electron-hole pairs are excited in a semiconductor, it is a priori not clear if subsequent relaxation leads to a gas of bound excitons or to an interacting plasma of unbound electrons and holes. In atomically thin transition metal dichalcogenide semiconductors, excitons are particularly important even at room temperature due to strong Coulomb interaction.
I will show how many-body methods can be combined with first-principle calculations to quantify the thermodynamic fission-fusion balance of excitons and electron-hole plasma. Due to the two-dimensional nature of these materials, the exciton-plasma balance can be efficiently tuned via the dielectric environment. We observe entropy ionization of excitons at low excitation densities and a Mott transition to a fully ionized plasma at high densities. Below the Mott transition, excitonic screening plays an important role in the description of the exciton-plasma balance. We propose the observation of these effects by studying exciton satellites in photoemission spectroscopy, which is sensitive to the single-particle spectral functions.