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Quasiparticle and optical properties of potential 2D materials

Date : Wednesday, July 10th, 2019 16:00 - 17:00 Place : Seminar Room 5 (A615), 6th Floor, ISSP Lecturer : Prof. Hung-Chung Hsueh Affiliation : Department of Physics, Tamkang University, Taiwan Committee Chair : Taisuke OZAKI (63258)
e-mail: t-ozaki@issp.u-tokyo.ac.jp

Quasi-2D atomically thin materials display a number of unique properties not found in their bulk counterparts, such as large self-energy and excitonic effects due to the quantum confinement and reduced screening with layer number close to the 2D limit. These atomically thin layer structures demonstrate rich physics and pave the way for emerging fields, such as excitonics and valleytronics, with great potential for applications in next-generation devices. To probe the dimensionality effects, we use ab initio GW+BSE methods based on many-body perturbation theory (MBPT) to explain and predict the quasiparticle and optical properties of potential quasi-2D semiconductors: monolayer group VI monochalcogenides (Ge,Sn/S,Se) and transition metal dichalcogenides (MoSe2 and Janus MoSSe). Significant exciton binding energy, layer-controlled bandgap, anisotropic optical response [1], and possible valley polarization [2] serve as a convenient and efficient method for engineering the excited-state properties of quasi-2D systems.

[1] Hung-Chung Hsueh, Jia-Xuan Li, and Ching-Hwa Ho, Adv. Optical Mater. 6, 1701194 (2018).
[2] Ang-Yu Lu, et.al, Nature Nanotechnology 12, 744 (2017).

 


(Published on: Monday July 1st, 2019)