In-plane interfacing effects of two-dimensional transition-metal dichalcogenide heterostructures.

In-plane heterostructures of two-dimensional transition-metal dichalcogenides (TMDs) demonstrate the formation of one-dimensional interfaces (or interlines), leading to new exciting properties and device functionalities. In this work, the interfacing effects have been studied in MoS2/WS2 quantum-well and superlattice in-plane heterostructures on the basis of first-principles electronic calculations. In light of the orbital-projected band structures, MoS2/WS2 in-plane heterostructures illustrate type-II band alignments with rather a small band offset for the valence band maximum and a relatively large band offset for the conduction band minimum. Upon increasing the width of TMD constituents, the band gap varies within a small range. In MoS2 and WS2, the surline energy and work function of zigzag edges with S-terminations are obviously higher than those of metal-terminations, and charge transfer from MoS2 to WS2 could be addressed due to the difference in the Fermi level. In-gap levels induced by S vacancies in MoS2/WS2 in-plane heterostructures are discrete and, interestingly, change to consecutive bands due to the built-in electric field.