研究目的
Investigating the dependence of band structure and exciton properties of encapsulated WSe2 monolayers on the hBN-layer thickness.
研究成果
The encapsulation of the WSe2 monolayer by only three sheets of hBN (～1 nm) already yields a 20% reduction of the exciton binding energy, whereas the maximal reduction for a thick hBN layer is ～27%. The quantum electrostatic heterostructure model tends to overestimate the reduction of the binding energies when compared to first-principles calculations.
研究不足
The computational setup does not allow the determination of the effect of dielectric screening on the excited states of the excitons.
1：Experimental Design and Method Selection:
The study involves solving the Bethe-Salpeter equation on top of GW wave functions in density functional theory calculations to investigate screening effects due to hBN surrounding layers.
2：Sample Selection and Data Sources:
WSe2 monolayers encapsulated by varying thicknesses of hBN layers.
3：List of Experimental Equipment and Materials:
Computational methods using the VASP package for DFT calculations, including the plane-augmented-wave scheme and the Perdew-Burke-Ernzerhof functional.
4：Experimental Procedures and Operational Workflow:
Geometry optimization of heterostructures at the PBE-D3 level, GW calculations for quasiparticle band structures, and solving the Bethe-Salpeter equation for optical spectra.
5：Data Analysis Methods:
Analysis of absorbance spectra and exciton binding energies as a function of hBN thickness.
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