Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.10: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Induced defect states in supported and freestanding MoS₂ monolayers — •Sven Mehrkens, Oleg Gridenco, Kathrin Sebald, Christian Tessarek, Martin Eickhoff, and Jürgen Gutowski — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Alle 1, D-28359 Bremen, Germany

Single-layer molybdenum disulfide (MoS₂) photoluminescence emission is strongly affected by the dielectric environment, i.e., of the supporting substrate. To avoid this, it is highly preferable to study the optical properties of freestanding monolayers. In this contribution an etching-free transfer method using polymethyl-methacrylate (PMMA) will be demonstrated, for the transfer of mechanically exfoliated MoS₂ flakes from SiO₂ substrates to a TEM grid. Localized excitons, trapped at vacancies are of considerable importance for the characteristics of optoelectronic devices. In MoS₂, vacancies can be introduced via Ga⁺ ion irradiation using a focused ion beam (FIB). A variation of the ion dose results in different densities of defect states, emitting at 1.75 eV for flakes on SiO₂ at 4 K. We compare the optical properties of freestanding and supported monolayers in order to investigate the influence of the dielectric environment on the introduced defect states.