Dielectric screening at TMD:hBN interfaces: Monolayer-to-bulk transition, local-field effect, and spatial dependence
Olugbenga Adeniran, Zhen–Fei Liu
Abstract
The dielectric effects of a substrate have been shown to be important for modulating the electronic properties of an adsorbate, especially in van der Waals heterostructures. Here, using the first-principles dielectric embedding $GW$ approach within the framework of many-body perturbation theory, we perform a case study on the dielectric screening effects of hexagonal boron nitride (hBN) on various transition-metal dichalcogenides (TMDs). We consider three systems, monolayer ${\mathrm{MoS}}_{2}$, bilayer ${\mathrm{MoS}}_{2}$, and a mixed ${\mathrm{WS}}_{2}/{\mathrm{MoS}}_{2}$ bilayer adsorbed on hBN, and examine three aspects of the substrate dielectric screening: (i) the thickness dependence and the monolayer-to-bulk transition, for which we consider the effects of one-, two-, three-, and four-layer hBN; (ii) the local-field effect, for which we numerically assess a common approximation of neglecting the in-plane local-field components of the substrate polarizability; and (iii) the spatial dependence, for which we consider the mixed ${\mathrm{WS}}_{2}/{\mathrm{MoS}}_{2}$ bilayer adsorbed on hBN with either side facing the substrate. Our results provide quantitative insight into how the substrate screening effects can be leveraged for band structure engineering.