Na-assisted fast growth of large single-crystal MoS 2 on sapphire

Monolayer molybdenum sulfide (MoS 2 ), a typical semiconducting transition metal dichalcogenide, has emerged as a perfect platform for next-generation electronics and optoelectronics due to its sizeable band gap and strong light–matter interactions. Nevertheless, the controlled growth of a monolayer MoS 2 single-crystal with a large-domain size and high crystal quality still faces great challenges. Herein, we demonstrate the fast growth of a large-domain monolayer MoS 2 on the c-plane sapphire substrate with the assistance of sodium chloride (NaCl) crystals as the intermediate promoter. Particularly, the volatilization temperature of the NaCl crystal and the growth temperature of MoS 2 are established to be the key parameters that influence the growth efficiency of MoS 2 at an optimized growth condition. Monolayer triangular MoS 2 domain with an edge length ∼300 μ m is obtained within 1 min, featured with a growth rate ∼5 μ m s –1 . The Na element from the NaCl crystal is found to be able to facilitate the two dimensional growth of monolayer MoS 2 . This work thus offers novel insights into the high-efficiency production of large-domain monolayer MoS 2 on insulating growth substrates.