Dependence of band structure and exciton properties of encapsulated WSe2 monolayers on the hBN-layer thickness

Article

关键词: SEMICONDUCTORS;    APPROXIMATION;    EXCITATIONS;    STATES;   

DOI  :  10.1103/PhysRevB.98.245126

来源: SCIE

【 摘 要 】

The optical properties of two-dimensional transition-metal dichalcogenide monolayers, such as MoS2 or WSe2 are dominated by excitons, Coulomb bound electron-hole pairs. Screening effects due to the presence of hexagonal-boron nitride (hBN) surrounding layers have been investigated by solving the Bethe-Salpeter equation on top of GW wave functions in density functional theory calculations. We have calculated the dependence of both the quasiparticle gap and the binding energy of the neutral exciton ground-state E-b as a function of the hBN-layer thickness. This paper demonstrates that the effects of screening at this level of theory are more short ranged than is widely believed. The encapsulation of a WSe2 monolayer by three sheets of hBN (similar to 1 nm) already yields a 20% decrease in E-b, whereas the maximal reduction is 27% for thick hBN. We have performed similar calculations in the case of a WSe2 monolayer deposited on stacked hBN layers. These results are compared to the recently proposed quantum electrostatic heterostructure approach.

【 授权许可】

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