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HL: Fachverband Halbleiterphysik

HL 20: 2D semiconductors and van der Waals heterostructures II (joint session HL/DS)

HL 20.10: Vortrag

Montag, 16. März 2020, 18:00–18:15, POT 81

Micro-photoluminescence studies of defects hosting localized excitons in single-layer MoS₂ — •Oleg Gridenco, Kathrin Sebald, Christian Tessarek, Martin Eickhoff, and Jürgen Gutowski — Institute of Solid State Physics, University of Bremen, D-28359 Bremen, Germany

Beside to free excitons, single-layer transition metal dichalcogenides (TMDs) can also host localized excitons that are bound to defect states and emit with energies smaller than the free-exciton energy. These localized emission centres often appear in as-prepared samples after exfoliation, but they can also be created or enhanced at specific positions by local engineering. In this talk, we will introduce our recent progress in the study of point defects in single-layer MoS₂. Defects were introduced by scanning a Ga⁺ ion beam over a certain area of a single-layer using a focused ion beam (FIB) machine. The number of defects was controlled by varying the Ga⁺ ion dose. By performing low-temperature micro-photoluminescence (µPL) spectroscopy we investigate the emission properties of localized excitons. Moreover, we found that the intentionally generated defect-related emission centres dominate the optical spectra of MoS₂ at low temperatures. Additionally, light emitted from free or localized excitons needs to be efficiently collected. Here we will discuss how plasmonic nanostructures on top of single-layers are particularly well suited for enhancing the quantum yield of single-layer TMDs.