Mixed‐Dimensional Epitaxy of Aligned 1D vdW Nanowires on Low‐Symmetry 2D vdW Materials: Sb 2 X 3 on ReX 2 (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 Sb 2 X 3 nanowires (X = S, Se) on low‐symmetry two‐dimensional (2D) vdW materials ReX 2 . The low symmetry of the substrate enables aligned growth, preferentially along the ±[001] direction of Sb 2 X 3 and ±[100] of ReX 2 , 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 Sb 2 S 3 /ReSe 2 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.