One-pot growth of 2D lateral superlattices via vapor phase modulation*

Here, we developed a one-pot synthesis strategy for the continuous fabrication of TMDs lateral superlattices (MoSe₂-WSe₂ and MoS₂-WS₂). These superlattices are sequentially created by only changing the composition of the reactive gas environment in the presence of water vapor. Water vapor allows selective oxidation and volatilization of Mo compound whereas reducing gas (H₂) facilities the vaporization of W compounds. The switching cycle between the water vapor and H₂ allows us to control the Mo and W domains, respectively, and hence the superlattice structure. The exact role of water vapor in the selective oxidation and reduction of solid precursor will be discussed. We found that this carrier gas switching cycle is very crucial for obtaining atomically sharp interfaces. Raman and Photoluminescence spatial mapping confirm the chemical and optical homogeneity of the distinct TMD domains in the heterostructures. Photoluminescence line scans revealed the effective modulation of the electronic transitions across the heterostructures. Transmission electron microscopy confirm high quality seamless lateral connectivity within a single-crystal heterostructure.