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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: 2D Materials IV (joint session HL/CPP)

CPP 32.1: Talk

Wednesday, March 29, 2023, 09:30–09:45, POT 81

Nonlinear optical characterization of atomically thin layers of the transition metal dichalcogenides WSe₂ and MoS₂ — •Henry Volker Hübschmann¹, Gerhard Berth¹, Ioannis Caltzidis¹, Katharina Burgholzer², Alberta Bonanni², and Klaus D. Jöns¹ — ¹Department of Physics, Paderborn University, 33098 Paderborn, Germany — ²Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, 4040 Linz, Austria

In the field of quantum technologies functional 2D-structures based on transition metal dichalcogenides like WSe₂ and MoS₂ represent a novel material platform due to their specific optical and electronic properties. In contrast to semimetallic graphene they feature an electronic band gap and a strong spinorbit coupling. Applications of such layered 2D-materials in functional structures are to be found within photonics, spinorbitronics or nanoelectronics. In this work we present our fundamental nonlinear study on mechanically exfoliated atomically thin layers of the semiconductors WSe₂ and MoS₂. In this context, the second harmonic generation was determined for both van der Waals layered material systems as a function of the layer number. The respective nonlinear behavior was proven by a power-dependent characterization and supplemented by polarimetric analysis. Nonlinear imaging of the flakes was successfully performed by confocal SH-microscopy. In a further step the oxidation of MoS₂ layered systems was analyzed, here it was shown that for an even number of layers the oxidation leads to a break of their centrosymmetric structure, which is manifested in the clear presence of a relatively strong second harmonic signal.