Homoepitaxial Growth of Large-Scale Highly Organized Transition Metal Dichalcogenide Patterns

Controllable growth of highly crystalline transition metal dichalcogenide (TMD) patterns with regular morphology and unique edge structure is highly desired and important for fundamental research and potential applications. Here, single-crystalline MoS₂ flakes are reported with regular trigonal symmetric patterns that can be homoepitaxially grown on MoS₂ monolayer via chemical vapor deposition. The highly organized MoS₂ patterns are rhombohedral (3R)-stacked with the underlying MoS₂ monolayer, and their boundaries are predominantly terminated by zigzag Mo edge structure. The epitaxial MoS₂ crystals can be tailored from compact triangles to fractal flakes, and the pattern formation can be explained by the anisotropic growth rates of the S and Mo edges under low sulfur chemical potential. The 3R-stacked MoS₂ pattern demonstrates strong second and third-harmonic-generation signals, which exceed those reported for monolayer MoS₂ by a factor of 6 and 4, correspondingly. This homoepitaxial growth approach for making highly organized TMD patterns is also demonstrated for WS₂ .