Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 20: 2D materials: Chalcogenides I (joint session HL/DS)

DS 20.11: Talk

Wednesday, March 14, 2018, 12:15–12:30, A 151

Electronic and optical properties of group-IV transition metal dichalcogenides monolayers and their heterostructures — •Ka Wai Lau, Caterina Cocchi, and Claudia Draxl — Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Germany

The interest in transition-metal dichalcogenides (TMDs) monolayers as promising materials for opto-electronics has rapidly increased in the last few years [1]. The majority of studies has been devoted so far to group-VI TMDs, with MoS2 and WS2 as the most relevant examples of this material class [1]. Here, we study monolayers of group-IV TMDs focusing on ZrS2 and HfS2. We investigate their electronic and optical properties in the framework of many-body perturbation theory (GW and the Bethe-Salpeter equation) as implemented in the all-electron full-potential code exciting [2]. The optical response of these systems is characterized by intense peaks in the visible region due to tightly-bound excitons with binding energies of the order of hundreds of meV. The degeneracy of the hole state at the Γ point with different dispersion along the M-Γ-K direction and the strong spin-orbit coupling in the valence band leads to several distinct excitonic states around Γ. Finally we study van-der-Waals heterostructures obtained by combining ZrS2 and HfS2 monolayers in view of understanding how different stacking patterns influence band alignment and optical excitations.

[1] K. F. Mak and J. Shan, Nat. Photon. 10, 216 (2016)

[2] A. Gulans et al., J. Phys.: Condens. Matter 26, 363202 (2014)