SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 78: Poster Session VI: 2D Materials: Electronic structure, excitations, etc. II
O 78.2: Poster
Mittwoch, 3. März 2021, 13:30–15:30, P
Analysis of interlayer excitons in the case of MoS2 on GaSe. — •Christian Wagner, Mahfujur Rahaman, Dietrich R.T. Zahn, and Sibylle Gemming — Institute of Physics, Technische Universität Chemnitz, Chemnitz, Germany
We study the formation of interlayer excitons in GaSe | MoS2 heterostacks as a function of layer composition from first principles in order to specifically tailor photon absorption in layered heterostacks.
The electronic interaction in semiconducting 2D layered material heterostacks is often reasonably described by a perturbation of the physical effects of the isolated homostacks. But their optical properties go beyond this picture of weak layer interaction: moiré potentials influence exciton dynamics and bound interlayer excitons may emerge. Interlayer excitons are composed of electron and hole states from different layers. These mixed states are measured experimentally by photoluminescence and photocurrents and predicted by theory, e.g. in MoS2 on GaSe [1].
The composition of all interlayer excitons are thoroughly analyzed by solving the Bethe-Salpeter equation for the heterobilayer of MoS2 on GaSe. The exciton Hamiltonian is diagonalized and the exciton wave functions are projected onto layers as a function of k-space. By means of density functional theory and optical selection rules, these optical interlayer transitions are extrapolated for larger heterostacks and compared directly with experiments.
[1] M. Rahaman, C. Wagner et al., J. Phys.: Condens. Matter 31, 114001 (2019).