Beyond-Grain-Boundary Growth of Twisted Bilayer MoS2

In the chemical vapor deposition (CVD) synthesis of two-dimensional materials, the meeting of crystal domains typically results in stitched grain boundaries accompanied by defects. In contrast, beyond-grain-boundary growth─where two individual domains retain their intact boundaries─is rarely observed or reported. Moreover, the large-scale synthesis of twisted transition metal dichalcogenides (TMDCs), particularly at small twist angles, is critical for advancing next-generation electronic and quantum technologies. Here, we report the beyond-grain-boundary growth of bilayer MoS2 across the full range of twist angles (0° to 60°) using a secondary sulfur supply strategy. A record lateral size of 46 μm was achieved in CVD-grown twisted TMDCs, along with a 10.4% yield of small twist angles (0°-10° and 50°-60°). For bilayer MoS2 with a twist angle of 3.4°, Moiré superlattices with a periodicity of 5.45 nm were observed. Systematic Raman and photoluminescence (PL) studies revealed significant twist-angle-dependent effects on the phonon and exciton properties. This unique growth behavior is attributed to edge structure modifications induced by an increased sulfur chemical potential. These results demonstrate an approach to synthesizing high-quality twisted 2D materials, contributing to progress in twistronics and quantum device applications.