Large-Area Aligned\nGrowth of Low-Symmetry 2D ReS<sub>2</sub> on a High-Symmetry Surface

The\nlarge-scale preparation of two-dimensional (2D) materials\nis\npivotal in unlocking their extensive potential for next-generation\nsemiconductor device applications. Wafer-scale single crystals of\na high-symmetry 2D material (e.g., graphene and molybdenum disulfide)\ncan be achieved by seamlessly stitching the aligned domains. However,\nachieving the alignment of low-symmetry 2D materials remains a great\nchallenge and is rarely reported. Rhenium disulfide (ReS<sub>2</sub>), one of the low-symmetry 2D materials, shows considerable promise\nfor optoelectronics, especially polarization-sensitive applications.\nHere, we report large-area chemical vapor deposition synthesis of\nhighly oriented, low-symmetry monolayer ReS<sub>2</sub> flakes on\na high-symmetry Au(111) surface, followed by seamless stitching into\na centimeter-scale continuous 2D film. Cross-sectional scanning transmission\nelectron microscopy reveals that the aligned monolayer ReS<sub>2</sub> flakes are guided by step edges on Au(111) surfaces along the [011̅]\ndirection. Additionally, 2D ReS<sub>2</sub> can flatten Au surfaces\nduring its growth through surface step bunching. The growth of the\nReS<sub>2</sub> monolayer demonstrates its ability to extend across\nAu surface steps and facets. Thus, we have established a reliable\nand robust synthesis route that accommodates different surface roughness\nconditions. The aligned and scalable film growth of low-symmetry 2D\nReS<sub>2</sub> significantly contributes to the in-depth understanding\nof epitaxial growth mechanisms for low-symmetry 2D materials, holding\npromise for advancing their future applications.