Role of the carrier gas flow rate in monolayer MoS₂ growth by modified chemical vapor deposition

Monolayer molybdenum disulfide (MoS₂) has attracted much attention because of the variety of potential applications. However, its controlled growth is still a great challenge. Here, we report a modified chemical vapor deposition method to grow monolayer MoS₂. We observed that the quality of the MoS₂ crystals could be greatly improved by tuning the carrier gas flow rate during the heating stage. This subtle modification prevents the uncontrollable reaction between the precursors, a critical factor for the growth of high-quality monolayer MoS₂. Based on an optimized gas flow rate, the MoS₂ coverage and flake size can be controlled by adjusting the growth time.