Iodine-assisted ultrafast CVD growth of high-quality monolayer MoS₂. (A) Scheme of the ultrafast growth approach. (B) OM image of MoS₂ grown with iodine-assisted CVD method in 5 s. (C) Domain sizes of MoS₂ grown with and without iodine-assisting during growth. (D) Comparison of the growth time and domain size of as-grown MoS₂ with other work. (E) HAADF-STEM image of the MoS₂. (F) Zoomed in image of the MoS₂ with mono-sulfur vacancy. The bottom panel is the corresponding intensity line profile along the red square. (G) Comparison of the sulfur vacancies of iodine-assisted grown MoS₂ with other work.