Interfacial properties of In-plane monolayer 2H-MoTe2/1T'-WTe2 heterostructures

One of the most appealing aspects of the two-dimensional transition-metal dichalcogenides (2D-TMDs) is that they have a variety of crystal types, which can exist in three different atomic lattices, 2H, 1 T and 1 T', and can therefore exhibit diverse electronic properties. In addition, 2D-TMD heterostructures with distinctive features can be generated by combining two monolayers either vertically or laterally (in-plane). In this work, we used first-principles calculations to explore the structural and electronic properties of the H-phase MoTe2 monolayer, the T'-phase WTe2 monolayer, and their in-plane heterostructures (H-MoTe2/T'-WTe2). The H-phase MoTe2 monolayer has a band structure with a direct band gap, whereas the 1 T'-WTe2 monolayer is projected to be a Weyl semimetal based on our findings. We constructed a series of five relatively stable in-plane H-MoTe2/T'-WTe2 heterostructures with metal–semiconductor and studied their electronic properties. The band structures of these in-plane heterostructures were shown to be strongly related to the relative orientations of the monolayers at the interface. In particular, the band gaps of the heterostructures joined along the armchair direction were found to be smaller than 0.1 eV. By sewing the MoTe2 and WTe2 monolayers along the zigzag direction, two relatively stable structures were created, with according to the band structure analysis, exhibited metallic characteristics. Surprisingly, band inversion appeared near the Fermi level due to boundary effects. Therefore, topological properties may be present in such in-plane heterostructures. Moreover, some of these in-plane H-MoTe2/T'-WTe2 heterostructures have effective Schottky barrier heights smaller than 0.25 eV for holes, and could thus be used to construct field effect transistors (FETs). We also found that the effective Schottky barrier height was largely determined by the interfacial bonding environment, the external electric field, and uniaxial strains. Our findings enrich the diversity of the 2D-TMDs heterostructures and point to a viable approach for the design of high-performance electronic and optoelectronic devices.