Many-body theory of optical absorption in doped two-dimensional semiconductors

Abstract

In this article, we use a many-body approach to study the absorption spectra of electron-doped two-dimensional semiconductors. Optical absorption is modeled by a many-body scattering Hamiltonian which describes an exciton immersed in a Fermi sea. The interaction between electron and exciton is approximated by an effective scattering potential, and optical spectra are calculated by solving for the exciton Green's function. From this approach, a trion state can be assigned as a bound state of an electron-exciton scattering process, and the doping-dependent phenomena observed in the spectra can be attributed to several many-body effects induced by the interaction with the Fermi sea. While the many-body scattering Hamiltonian can not solved exactly, we reduce the problem to two limiting solvable situations. The first approach approximates the full many-body problem by a simple scattering process between the electron and the exciton, with a self-energy obtained by solving a Bethe-Salpeter equation (BSE). An alternate approach assumes an infinite mass for the exciton, such that the many-body scattering Hamiltonian reduces to a Mahan-Nozieres-De Dominicis (MND) model. The exciton Green's function can then be solved numerically exactly by a determinantal formulation, and the optical spectra show signatures of the Fermi-edge singularity at high doping densities. The full doping dependence and temperature dependence of the exciton and trion lineshapes are simulated via these two approximate approaches, with the results compared to each other and to experimental expectations.

17 pages, 4 figures

References in corpus (9)

• Many-Body Theory of Trion Absorption Features in Two-Dimensional Semiconductors
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• Highly polarized Fermi gases in two dimensions
• Trion Species-Resolved Quantum Beats in MoSe2
• Quasiparticle effective mass divergence in two dimensional electron systems
• Fermi-edge exciton-polaritons in doped semiconductor microcavities with finite hole mass
• Many-body effects of a two-dimensional electron gas on trion-polaritons
• Generalized Galitskii approach for the vertex function of a Fermi gas with resonant interaction

Cited by in corpus (6)

• Electron-exciton interactions in the exciton-polaron problem
• A Many-Body Theory of the Optical Conductivity of Excitons and Trions in Two-Dimensional Materials
• Many-body exciton and inter-valley correlations in heavily electron-doped WSe${}_2$ monolayers
• A colloquium on the variational method applied to excitons in 2D materials
• Excitonic theory of doping-dependent optical response in atomically thin semiconductors
• Doping-induced non-Markovian interference causes excitonic linewidth broadening in monolayer WSe${}_2$