Atomically resolved two-dimensional amorphous nuclei formed during MoS₂ chemical vapor deposition

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Scalable manufacturing of 2D materials requires precise control over nucleation and growth.
• Molybdenum disulfide (MoS2) is a key 2D material with diverse applications.

Purpose of the Study:

• To investigate the atomic-scale mechanisms of MoS2 nucleation and growth during chemical vapor deposition (CVD).
• To provide mechanistic insights for controlled synthesis of high-quality 2D materials.

Main Methods:

• In situ atomic-scale observation using environmental transmission electron microscopy (ETEM).
• Molecular dynamics (MD) simulations to complement experimental findings.

Main Results:

• Initial nucleation involves the formation of a 2D amorphous structure.
• A structural ordering transition to a crystalline nucleus occurs upon reaching critical size.
• Observation of nuclei merging and oriented attachment, crucial for 2D single-crystal formation.

Conclusions:

• Elucidated the atomistic structural evolution during MoS2 nucleation and growth under CVD.
• Findings offer mechanistic insights for controlled synthesis of high-quality 2D crystals.
• Informs broader strategies for synthesizing covalently bonded material systems.