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DS: Fachverband Dünne Schichten
DS 4: 2D semiconductors and van der Waals heterostructures I (joint session HL/DS/O)
DS 4.8: Vortrag
Montag, 16. März 2020, 11:45–12:00, POT 81
Interlayer excitons and band alignment in MoS2/GaSe heterostructures. — •Christian Wagner1,2, Mahfujur Rahaman2, Dietrich R.T. Zahn2, and Sibylle Gemming1,2 — 1Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 2Institute of Physics, Technische Universität Chemnitz, Chemnitz, Germany
We study the influence of the (GaSe)n/(MoS2)m heterostack composition on the band alignment and the interlayer exciton energy using ab initio calculations.
The electronic interaction between individual layers in a 2D heterostack is often reasonably described by a perturbation of the physical effects of the isolated layers by additional electrostatic doping and screening. In terms of optical properties, however, the formation of bound interlayer excitons composed of electrons from one layer and holes from the neighboring layer is possible. These states are measured experimentally by photoluminescence and photocurrents, e.g. in the case of MoS2 on GaSe due to its type-II band alignment [1].
The interlayer excitons can be approximately located in k-space and energy from density functional theory by relating the band structures of the heterostack to the band structure of the individual layers.
This is allowed due to the weak hybridization of electronic states between the two materials.
Furthermore, the many-body description allows extracting the exciton binding energies and oscillator strengths in order to obtain the respective spectral signatures.
[1] M. Rahaman et al., J. Phys.: Condens. Matter 31, 114001 (2019)