Mixed-Dimensional Epitaxy of Aligned 1D vdW Nanowires on Low-Symmetry 2D vdW Materials: Sb2X3 on ReX2 (X = S, Se).

The creation of heterostructures from materials, and in particular van der Waals (vdW) materials, of different dimensionalities enables not only a combination of their intrinsic properties but also the emergence of novel functionalities absent in the individual components. However, most reported mixed-dimensional heterostructures are produced by physical assembly, with limited control over the materials' respective orientation and hence ill-defined interfaces. Here we demonstrate the epitaxial growth of a prototypical series of mixed-dimensional vdW heterostructures consisting of one-dimensional (1D) vdW materials Sb2X3 nanowires (X = S, Se) on low-symmetry two-dimensional (2D) vdW materials ReX2. The low symmetry of the substrate enables aligned growth, preferentially along the ±[001] direction of Sb2X3 and ±[100] of ReX2, with well-defined interfaces consistent with epitaxy. Notable findings include strong correlation between nanowire morphology and crystallographic orientation, with stacking fault defects acting as a strain relaxation mechanism. To validate the functional potential of these oriented interfaces, optoelectronic characterization of Sb2S3/ReSe2 p-n photodiodes showed photovoltaic behavior with 0.864 A/W responsivity at zero bias. These results establish vdW epitaxy on low-symmetry substrates as a promising strategy for the creation of aligned mixed-dimensional vdW heterostructures with well-defined interfaces, with potential applications in optoelectronics.