Atomically resolved two-dimensional amorphous nuclei formed during MoS <sub>2</sub> chemical vapor deposition
H. Ye, Chongteng Wu, Duanyun Cao, Guorui Zhang, Yinghui Sun, Yuchen Zhu, Feng Wu, Zhihong Zhang, R. R. Wang
Abstract
Control over the nucleation and growth of two-dimensional (2D) materials is essential for their scalable manufacturing. We report in situ atomic-scale observations of molybdenum disulfide (MoS 2 ) nucleation and growth through chemical vapor deposition (CVD) using environmental transmission electron microscopy. Coupled with molecular dynamics simulations, our observations reveal the formation of a 2D amorphous structure at the initial nucleation stage, which undergoes an in-plane structural ordering transition into a crystalline nucleus once a critical size is reached. We further captured nuclei merging and oriented attachment processes in the early growth stage, which likely contributed to 2D single-crystal fabrication. These findings unveil the atomistic structural evolution in MoS 2 nucleation and growth under CVD condition, providing mechanistic insight for the controlled synthesis of high-quality 2D crystals and informing broader strategies for covalently bonded material systems.