posted on 2020-03-20, 12:08authored byW. T. Geng, V. Wang, Y. C. Liu, T. Ohno, J. Nara
To have a fully first-principles
description of the moiré
pattern in transition-metal dichalcogenide heterobilayers, we have
carried out density functional theory calculations on a MoTe2(9 × 9)/MoS2(10 × 10) stacking, which has a
superlattice larger than an exciton yet not large enough to justify
a continuum model treatment. Lattice corrugation is found to be significant
in both monolayers, yet its effect on the electronic properties is
marginal. We reveal that the variation of the average local potential
near Mo atoms in both MoTe2 and MoS2 layers
displays a conspicuous moiré pattern. They are the intralayer
moiré potentials correlating closely with the spatial variation
of the valence band maximum and conduction band minimum. The interlayer
moiré potential, defined as the difference between the two
intralayer moiré potentials, changes roughly in proportion
to the band gap variation in the moiré cell. This finding might
be instructive in chemical engineering of van der Waals bilayers.