Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures

Abstract

The van der Waals interaction in vertical heterostructures made of two-dimensional (2D) materials relaxes the requirement of lattice matching, therefore enabling great design flexibility to tailor novel 2D electronic systems. Here we report the successful growth of MoSe2 on single-layer hexagonal boron nitride (hBN) on the Ru(0001) substrate using molecular beam epitaxy. Using scanning tunnelling microscopy and spectroscopy, we found that the quasi-particle bandgap of MoSe2 on hBN/Ru is about 0.25 eV smaller than those on graphene or graphite substrates. We attribute this result to the strong interaction between hBN/Ru, which causes residual metallic screening from the substrate. In addition, the electronic structure and the work function of MoSe2 are modulated electrostatically with an amplitude of ∼0.13 eV. Most interestingly, this electrostatic modulation is spatially in phase with the Moiré pattern of hBN on Ru(0001) whose surface also exhibits a work function modulation of the same amplitude.

Hexagonal MoTe2 with Amorphous BN Passivation Layer for Improved Oxidation Resistance and Endurance of 2D Field Effect Transistors

“…Boron nitride has emerged as a dielectric counterpart to TMDs due to its chemical stability, lack of dangling bonds, and wide bandgap (5.97 eV) characteristics 17 . Most notably, hexagonal boron nitride (h-BN), which has a similar crystal structure to graphene 18 , can be exfoliated onto various 2D materials to form heterostructures such as h-BN-MoS 2 19 – 21 , h-BN-WS 2 22 , h-BN-MoSe 2 23 , and BN-WSe 2 -BN 24 with remarkable electrical properties 25 . While these studies clearly demonstrate the benefit of h-BN packaging with TMD for improved mobility, on/off ratio, and thermal management, the challenge of exfoliation routes for such 2D heterostructure device assemblies is prohibitive for the scalable and cost-effective device production, leading to the search of alternative routes for h-BN synthesis and integration with TMD structures 18 .…”

Electronic Properties of Transferable Atomically Thin MoSe2/h-BN Heterostructures Grown on Rh(111)

“…The concept of vdW epitaxy was first proposed by Koma et al in the 1990s, and a wide variety of 2D materials have been studied since then. 6,14−17 However, the MBE growth of 2D vdW heterostructures such as MoSe 2 /h-BN 15 needs further study, and methods for transferring the resulting heterostack from the metallic substrate also need to be developed.…”

“…Surprisingly, the 3D nanomesh morphology of BN disappears during MoSe 2 growth, resulting in an atomically flat surface over the length of the substrate, with each layer preserving its lattice constant, in contrast with a previous work on MoSe 2 /h-BN/Ru(0001) systems. 15 We have also succeeded in transferring the resulting stacks onto insulating substrates. The ML MoSe 2 /h-BN heterostructure after transfer shows photoluminescence (PL) with the main peak at 1.57 eV at room temperature.…”

First-principles study of nonmetal doped monolayer MoSe2 for tunable electronic and photocatalytic properties

“…TMDCs family has more than 40 compounds (including MoS 2 , WS 2 , MoSe 2 , WSe 2 and WTe 2 etc ) with the formula of MX 2 9 , 10 . These TMDCs materials have been obtained by micromechanical exfoliation or liquid exfoliation (due to the weak van der Waals bonding interactions in the adjacent sandwiched layers) 11 – 13 , chemical vapor deposition (CVD) 14 and molecular beam epitaxy (MBE) 15 , 16 . However, vacancies inevitably occur in the growth process of TMDCs 17 – 19 .…”