Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: HL Poster I
HL 12.2: Poster
Montag, 1. April 2019, 17:30–20:00, Poster E
Defect-induced photoluminescence of WS2 monolayers — •Aswin Asaithambi1, Roland Kozubek1, Guenther Prinz1, Francesso Reale2, Cecelia Mattevi2, Marika Schleberger1, and Axel Lorke1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Duisburg, Germany — 2Department of Materials, Imperial College London, London, UK
The transition metal dichalcogenide tungsten di-sulphide (WS2) has a layered structure with an indirect band gap, which becomes direct at the K point in momentum space if only a monolayer is present. This leads to strongly enhanced photoluminescence (PL), compared to the bulk. However, WS2 monolayers are not defect free and the defects present in the material affect their emission properties drastically, which makes it necessary to study and characterize their influence.
In this contribution, we present highly sensitive, non-destructive, temperature- and power- dependent PL measurements to study defects in WS2 monolayers. WS2 monolayers were irradiated with different fluences of Xe30+ ions to create defects (presumably S and W vacancies) with different densities. Room temperature (RT) PL shows no defect-bound emission. Low temperature (LT) PL spectra of irradiated samples show new defect-related emission lines. Interestingly, those new defect-related peaks were annealed when subjected to higher laser power at both RT and LT. These results will be discussed in the frame of excitons, vacancy defect states and possible adsorbates, and compared with literature.