Controlled Synthesis of Highly Crystalline MoS₂ Flakes by Chemical Vapor Deposition

TLDR

The controlled synthesis of highly crystalline MoS₂ atomic layers remains a challenge for practical applications of this emerging material. The study aimed to develop a method for synthesizing rhomboid‑shaped MoS₂ flakes with a controlled number of layers. This was achieved by layer‑by‑layer sulfurization of MoO₂ microcrystals. The resulting flakes exhibited ~10 µm crystalline domains—larger than those from other methods—and enabled back‑gated FETs with performance comparable to mechanically exfoliated flakes, demonstrating a simple route to highly crystalline MoS₂ for fundamental and applied use.

Abstract

The controlled synthesis of highly crystalline MoS2 atomic layers remains a challenge for the practical applications of this emerging material. Here, we developed an approach for synthesizing MoS2 flakes in rhomboid shape with controlled number of layers by the layer-by-layer sulfurization of MoO2 microcrystals. The obtained MoS2 flakes showed high crystallinity with crystal domain size of ~10 μm, significantly larger than the grain size of MoS2 grown by other methods. As a result of the high crystallinity, the performance of back-gated field effect transistors (FETs) made on these MoS2 flakes was comparable to that of FETs based on mechanically exfoliated flakes. This simple approach opens up a new avenue for controlled synthesis of MoS2 atomic layers and will make this highly crystalline material easily accessible for fundamental aspects and various applications.