Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 57: Focus Session: Many-body effects in two-dimensional materials
O 57.7: Talk
Wednesday, March 9, 2016, 12:15–12:30, H16
Microscopic modeling of the homogeneous linewidth in absorption spectra of TMDs — •Malte Selig1, Gunnar Berghäuser2, Ermin Malic2, and Andreas Knorr1 — 1Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — 2Chalmers University of Technology, Department of Physics, SE-412 96 Gothenburg, Sweden
Monolayer transition metal dichalcogenides (TMDs) are direct-gap semiconductors with strong light-matter and Coulomb interaction. The latter accounts for strongly bound excitons, which dominate the optical spectrum. Here, we investigate the homogeneous linewidth in excitonic spectra induced by radiative coupling and exciton-phonon scattering. In conventional semiconductors, the radiative dephasing / recombination is typically weak in comparison to the electron-phonon scattering which mainly determines the homogeneous linewidth. The situation turns out to be different in atomically thin TMDs. Based on the density matrix formalism combined with the tight-binding approximation, we explicitly calculate the dephasing rates stemming from exciton-radiation interaction and exciton-phonon scattering. We find that in TMDs the radiative coupling is in the range of 1 meV clearly exceeding the exciton-phonon rate. We systematically investigate the resulting homogenous linewidth in absorption spectra of the most prominent TMDs for different temperatures, dopings, and substrates. [1]
[1] Galan Moody et al. Nat Commun 6, 8315 (2015)