Fabrication of van der Waals heterostructures through direct growth of rhenium disulfide on van der Waals surfaces

The growth of van der Waals (vdW) heterostructures has been desired to achieve two-dimensional (2D) layered heterostructures with various types of junctions for new functional device applications. ReS2 is one of the most promising semiconducting 2D materials for providing new electronic and optoelectronic properties when integrated into a vdW heterostructure. However, owing to its low-symmetry distorted 1T crystalline structure, there are few reports on continuous high-quality vdW heterostructures unlike those on 2D materials with a symmetric 2H crystalline structure. Herein, we report on the first demonstrated ReS2/HfS2 and ReS2/h-BN vdW heterostructures through the direct growth of ReS2 films on exfoliated HfS2 and h-BN with symmetric 1T (HfS2) and 2H (h-BN) crystalline structures. Few-layered continuous ReS2 films were grown on vdW surfaces of exfoliated 2D material flakes with highly crystalline structures, and the growth behavior is explained through a surface-dependent direct growth process with vdW epitaxy. This work verifies that symmetry-free direct growth of 2D vdW heterostructures can be achieved using a 2D material as the growth template with a high growth rate, which provides a path for developing various types of multi-functional vdW heterostructures.