Physical-form engineering of metal precursors regulates two-dimensional TMD growth

The chemical vapor deposition of two-dimensional transition metal dichalcogenides (TMDs) is highly sensitive to the temporal evolution of metal precursor supply, while the volatilization of conventional powder sources remains difficult to control. Here, we demonstrate that engineering the physical form of metal-oxide precursors through a molten-salt-assisted melting–resolidification treatment measurably changes the growth outcome. Compared with the same nominal oxide/NaCl composition used directly as a loose powder, the pre-solidified source yields more spatially uniform photoluminescence responses and narrower linewidth distributions. This strategy enables TMD films across sulfide, selenide, and telluride systems. Furthermore, by using spatially separated pre-solidified metal sources and different temperature programs, lateral and vertical heterostructure morphologies can be reproducibly obtained within the same reactor configuration. These findings establish physical-form engineering of metal precursors as a practical approach for regulating two-dimensional TMD growth.