Band alignment and interlayer hybridisation in transition metal dichalcogenide/hexagonal boron nitride heterostructures

Abstract

In van der Waals heterostructures, the relative alignment of bands between layers, and the resulting band hybridisation, are key factors in determining a range of electronic properties. This work examines these effects for heterostructures of transition metal dichalcogenides (TMDs) and hexagonal boron nitride (hBN), an ubiquitous combination given the role of hBN as an encapsulating material. By comparing results of density functional calculations with experimental angle-resolved photoemission spectroscopy (ARPES) results, we explore the hybridisation between the valence states of the TMD and hBN layers, and show that it introduces avoided crossings between the TMD and hBN bands, with umklapp processes opening ‘ghost’ avoided crossings in individual bands. Comparison between DFT and ARPES spectra for the MoSe2/hBN heterostructure shows that the valence bands of MoSe2 and hBN are significantly further separated in energy in experiment as compared to DFT. We then show that a novel scissor operator can be applied to the hBN valence states in the DFT calculations, to correct the band alignment and enable quantitative comparison to ARPES, explaining avoided crossings and other features of band visibility in the ARPES spectra.

WSe2/BN Heterostructure as the saturable absorber for a diode-pumped passively Q-switched 2 μm solid-state laser

“…On the one hand, BN has profound thermal conductivity, which is conducive to heat dissipation and can reduce the thermotropic damage of the heterojunction and improve the thermal and mechanical properties of the composites. On the other hand, due to its adjustable wide electronic bandgap and excellent dielectric properties, that is, BN is often act as an optoelectronic device by forming heterojunctions with other 2D materials, which in result promotesthe optical aspects and electrical properties of the composites [40] .…”