Artificial van der Waals heterostructures of 2D layered materials are attractive from the viewpoint of the possible discovery of new physics together with improved functionalities. Stacking various combinations of atomically thin semiconducting transition metal dichalcogenides, MX 2 (M = Mo, W; X = S, Se, Te) with a hexagonal crystal structure, typically leads to the formation of a staggered Type II band alignment in the heterostructure, where electrons and holes are confined in different layers. Here, the comprehensive studies are performed on heterostructures prepared from monolayers of WSe 2 and MoTe 2 using differential reflectance, photoluminescence (PL), and PL excitation spectroscopy. The MoTe 2 /WSe 2 heterostructure shows strong PL from the MoTe 2 layer at ≈1.1 eV, which is different from the quenched PL from the WSe 2 layer. Moreover, enhancement of PL intensity from the MoTe 2 layer is observed because of the near-unity highly efficient photocarrier transfer from WSe 2 to MoTe 2 . These experimental results suggest that the MoTe 2 /WSe 2 heterostructure has a Type I band alignment where electrons and holes are confined in the MoTe 2 layer. The findings extend the diversity and usefulness of ultrathin layered heterostructures based on transition metal dichalcogenides, leading to possibilities toward future optoelectronic applications.

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