High-Temperature In Situ Investigation of Chemical Vapor Deposition to Reveal Growth Mechanisms of Monolayer Molybdenum Disulfide
Hao Xue, Guozheng Wu, Bojin Zhao, Di Wang, Xiaoming Wu, Zhanggui Hu
Abstract
In situ investigation of chemical vapor deposition (CVD) is of critical importance to understanding growth mechanisms of transition-metal dichalcogenides (TMDs) and to develop technologies for growing high-quality monolayer single crystals. However, the in situ investigation is still a great challenge in practice, because TMD CVD growth is conducted at a high temperature with a reduction environment. In this work, we developed an in situ investigation system for CVD growth and presented real-time observations of monolayer MoS2 deposition on the SiO2/Si substrate. We discovered that monolayer MoS2 should be grown via the vapor-state precursor reaction and crystallized from the prenucleation sites on a substrate, an intermediate-phase MoO2 was essential for the nucleation seeding, but the population density should be controlled, and a high-concentration S vapor promoted the in-plane epitaxial growth of MoS2; hence, it was of great benefit to obtain a high-quality monolayer with a compact shape.