Diffusion-Mediated Synthesis of MoS2/WS2 Lateral Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional transition metal dichalcogenide (TMD) lateral heterostructures offer tunable electronic and optoelectronic properties.
• Controlled synthesis is crucial for realizing their potential in advanced devices.
• Current methods primarily rely on growth chronology for compositional control.

Purpose of the Study:

• To investigate the role of in-plane diffusion in the chemical vapor deposition (CVD) of MoS2/WS2 lateral heterostructures.
• To demonstrate that diffusion, not just growth order, dictates heterostructure composition.
• To explore the synthesis of novel lateral TMD heterostructures.

Main Methods:

• Chemical vapor deposition (CVD) of MoS2/WS2 lateral heterostructures.
• Optical, structural, and compositional analysis of synthesized TMD crystals.
• Systematic variation of growth temperatures and diffusion stages.

Main Results:

• In-plane diffusion significantly influences the composition of lateral TMD heterostructures.
• Nontrivial structures with compositions deviating from growth order were observed.
• Compositional mixing is favored at high growth temperatures, while segregation occurs at low temperatures.
• A diffusion mechanism controlling heterostructure formation was identified.

Conclusions:

• In-plane diffusion is a critical factor in synthesizing lateral TMD heterostructures.
• This mechanism allows for the creation of complex heterostructures not achievable through traditional methods.
• The findings expand the design space for future 2D material-based electronic and optoelectronic devices.