Mesoscale Epitaxy in Two-Dimensional Anisotropic ReS₂/MoS₂Vertical Heterostructures

Effects of lattice mismatch and twist on epitaxy in two-dimensional (2D) vertical heterostructures are well-explored, whereas the effects of in-plane anisotropy are largely unknown. Here, we report the synthesis of ReS₂/MoS₂ vertical heterostructures using chemical vapor deposition, combining anisotropic (triclinic) ReS₂ and isotropic (hexagonal) MoS₂. A combination of scanning/transmission electron microscopy (S/TEM) and density functional theory calculations are used to elucidate the microstructure of ReS₂/MoS₂ heterostructures and reveal a complex interplay of interfacial epitaxy, lattice mismatch strain, and anisotropy. We observe that the heterostructure system’s ability to relax interlayer registry differs in the crystallographic directions of larger and smaller lattice mismatch. It nevertheless obtains an overall effective lattice registry on the longest length scales by means of variations in the Re chain direction that create a quilt-like pattern of stripe domains, a phenomenon we describe as mesoscale epitaxy.