Effect of hydrogen on the growth of MoS2 thin layers by thermal decomposition method

•Large-area MoS2 thin layers were synthesized by the thermolysis of (NH4)2MoS4 film.•The structure and growth mechanism of MoS2 thin layers has been investigated.•MoO3 can be easily formed which will dramatically degrade the quality of MoS2 film.•Unexpected Mo oxidation can be completely prevented when H2 flux reaches 100 sccm.

Large-area MoS2 thin layers have been synthesized onto the SiO2/Si substrate by the thermolysis of (NH4)2MoS4 film. The structure and growth mechanism of MoS2 thin layers have been investigated. The results reveal that MoO3 can be easily formed during the growth process of MoS2 film, which will dramatically degrade the quality of MoS2 film. Further studies show that with increasing hydrogen fluxes, the content of MoO3 will decrease, and when the hydrogen flux reaches 100 sccm, pure MoS2 film can be obtained. It means that hydrogen plays a critical factor for synthesis of high-quality MoS2 thin layers without unexpected Mo oxidation. This work is beneficial for not only the fundamental understanding of growth mechanism, but also the potential applications of MoS2 film in electronics.