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HL: Fachverband Halbleiterphysik
HL 53: 2D Materials and Heterostructures: (Twisted) Bilayers (joint session HL/TT)
HL 53.3: Talk
Friday, March 22, 2024, 10:00–10:15, EW 201
Electrical tuning of moiré excitons in MoSe2 bilayers — •Joakim Hagel1, Samuel Brem2, and Ermin Malic2,1 — 1Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden — 2Department of Physics, Philipps University of Marburg, 35037 Marburg, Germany
Recent advances in the field of vertically stacked 2D materials have revealed a rich exciton landscape. In particular, it has been demonstrated that out-of-plane electrical fields can be used to tune the spectral position of spatially separated interlayer excitons. Other studies have shown that there is a strong hybridization of exciton states, resulting from the mixing of electronic states in both layers. However, the connection between the twist-angle dependent hybridization and field-induced energy shifts has remained in the dark. Here, we investigate on a microscopic footing the interplay of electrical and twist-angle tuning of moiré excitons in homobilayers [1,2]. We reveal distinct energy regions in PL spectra that are clearly dominated by either intralayer or interlayer excitons, or even dark excitons [1]. Consequently, we predict twist-angle-dependent critical electrical fields at which the material is being transformed from a direct into an indirect semiconductor [1]. Our work provides new microscopic insights into experimentally accessible knobs to significantly tune the moiré exciton physics in atomically thin nanomaterials.
[1] J. Hagel, S. Brem, E. Malic, 2023 2D Mater. 10 014013
[2] Tagarelli, F., Lopriore, E., Erkensten, D. et al. Nat. Photon. 17, 615-621 (2023)
Keywords: Excitons; Electrical Tuning