Excitons in atomically thin transition metal dichalcogenides

By Gang Wang, A. Chernikov, M. M. Glazov, T. Heinz, Xavier Marie, T. Amand, Bernhard Urbaszek. 2017

717 citations recorded by the source corpus.

Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. Here we review recent progress in our understanding of the excitonic properties in monolayer TMDs and lay out future challenges. We focus on the consequences of the strong direct and exchange Coulomb interaction, discuss exciton-light interaction and effects of other carriers and excitons on electron-hole pairs in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observed in applied electric and magnetic fields is summarized.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/fd2b502270bd8e09c27d75305e4b1547fe6b5970

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Citations in the corpus

WSe 2 2D p‐type semiconductor‐based electronic devices for information technology: Design, preparation, and applications (2020, background): “The dissociation of exciton, 135 typically demanding a built-in electric field 136,137 in WSe 2 becomes of vital importance because an e-h pair bonded together with Coulombic interaction 138 cannot be separated with kinetic energy at room temperature.”
Quantum Simulators: Architectures and Opportunities (2019, background): “2D material heterostructures can also host high densities of long-lived bosonic particles such as excitons and exciton-polaritons, manipulable to produce highly tunable solid-state platforms to simulate bosonic many-particle systems, and to realize optoelectronic and thermoelectric applications [102”
Exciton physics and device application of two-dimensional transition metal dichalcogenide semiconductors (2018, background): “e phenomena, such as the formation of different types of excitons including optically allowed and forbidden dark excitons (Fig. 2a), as well as spatially separated interlayer exciton states (Fig. 2b) [43, 44, 45, 46, 47, 48]. They exhibit binding energies in the range of 0.5 eV, which is one to two ”
Broadband optical properties of monolayer and bulk MoS2 (2020, methodology): “(2) Optical constants of the MoS2 monolayer are fitted point-by-point(54) to ellipsometry spectra using the Levenberg–Marquardt algorithm.”