Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 53: 2D Semiconductors and van der Waals Heterostructures V
HL 53.7: Vortrag
Donnerstag, 20. März 2025, 16:45–17:00, H15
Trion saturation and trion filtering in MoS2 and MoS2/graphene heterostructures — Omid Ghaebi1, Tarlan Hamzayev1, •Till Weickhardt1, and Giancarlo Soavi1,2 — 1Institute of Solid State Physics, Friedrich Schiller University Jena — 2Abbe Center of Photonics, Friedrich Schiller University Jena
Optical excitation of electron-hole pairs in transition-metal dichalcogenides leads to the formation of excitons, that can join with free carriers to form trions [1]. Since trions display an efficient non-radiative decay, tuning their relative density with respect to neutral excitons by external knobs is fundamental to engineer the light emitting efficiency of TMD opto-electronic devices. In this work, we investigate the interplay of excitons, trions, and free electrons with regards to gating and excitation power. By carrying out these experiments on a pristine MoS2 monolayer as well as on a MoS2/graphene heterostructure where the graphene facilitates fast charge transfer from the TMD [2,3], we study the interdependent dynamic of excitons and trions. Most prominently, this effect can be seen in a super-linear power-scaling of the exciton density due to saturation of trions in the monolayer MoS2 [4]. When the graphene is added to form the heterostructure, this effect vanishes due to the elimination of trions.
[1] Mak et al. Nature Mater 12, 207-211 (2013). [2] Lorchat et al. Nat. Nanotechnol. 15, 283-288 (2020). [3] Küchle et al. Opt. Mater.: X 12, 2590-1478 (2021). [4] Wang et al. ACS Photonics 10 (2), 412-420 (2023).
Keywords: trions; charge transfer