Moire Potential, Lattice Corrugation, and Band Gap Spatial Variation in a Twist-Free MoTe2/MoS2 Heterobilayer

To have a fully first-principles description of the moire pattern in transition-metal dichalcogenide heterobilayers, we have carried out density functional theory calculations on a MoTe2(9 x 9)/MoS2(10 x 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 moire pattern. They are the intralayer moire potentials correlating closely with the spatial variation of the valence band maximum and conduction band minimum. The interlayer moire potential, defined as the difference between the two intralayer moire potentials, changes roughly in proportion to the band gap variation in the moire cell. This finding might be instructive in chemical engineering of van der Waals bilayers.