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HL: Fachverband Halbleiterphysik

HL 27: 2D semiconductors and van der Waals heterostructures III (joint session HL/DS)

HL 27.2: Talk

Tuesday, March 17, 2020, 10:00–10:15, POT 81

Control of Excitons in Monolayer Transitionmetal Dichalcogenides via Extrinsic Dielectric Screening — •Frederik Otto, Philip Klement, and Sangam Chatterjee — Institute of Experimental Physics I, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany

Electric field lines between charges in freestanding monolayers of transition metal dichalcogenides (TMDs) can extend freely outside the material’s perimeters due to the absence of screening carriers on top and on the bottom of the sample. Similarly, field lines extending into a close dielectric, e.g., the substrate, are subject to extrinsic screening effects. This effectively weakens the Coulomb interaction of charge carriers and therefore, iduces changes to the exciton binding energy and electrical band gap.
In order to obtain knowledge about the interaction range and the effect of the static dielectric constant of the surrounding dielectric environment on A and B-excitons of the K-point, we investigated monolayer samples WSe₂ supported on either TiO₂ (high static dielectric constant) or SiO₂ (low static dielectric constant) and samples encapsulated between the two substrate materials.