Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 28: 2D materials: Chalcogenides II (joint session HL/DS)

DS 28.14: Talk

Thursday, March 15, 2018, 13:00–13:15, A 151

Band Gaps and Carrier Relaxation in Thin Films of ZrS₃ — •Christopher Belke¹, Sonja Locmelis², Johannes C. Rode¹, Hennrik Schmidt¹, Bastian Hoppe², Peter Behrens², and Rolf J. Haug¹ — ¹Institut für Festkörperphysik, Leibniz Universität Hannover, 30167 Hannover, Germany — ²Institut für Anorganische Chemie, Leibniz Universität Hannover, 30167 Hannover, Germany

New varieties of two-dimensional crystals [1] are currently getting into focus of the material sciences. An example for such layered materials are Transition Metal Trichalcogenides. Here we study the compound ZrS₃: bulk crystals were synthesized by chemical gas transport; stoichiometry and structure were verified by powder X-ray diffractometry and energy-dispersive X-ray spectroscopy (EDX), and analyzed by absorption measurements. The latter indicate an indirect bandgap of about 1.8 eV and a direct bandgap of 2.3 eV, which differ slightly from literature values [2, 3]. Thin flakes are exfoliated and contacted. Conductivity measurements are investigated in response to illumination with LEDs of different wavelengths. We observe a pronounced rise in conductivity between 2.1 eV and 2.4 eV which is in good agreement with the direct bandgap found in the absorptions measurements. Measurements of charge carrier relaxation are described by a power-law dependence and reveal unexpectedly long relaxation times.

[1] A. K. Geim, I. V. Grigorieva, Nature 499, 419-425 (2013).

[2] M. Abdulsalam, D. Joubert, Eur. Phys. J. B. 88, 177 (2015).

[3] Y. Jin, X. Li, J. Yang, Phys. Chem. Chem. Phys. 17, 18665 (2015).