Size-dependent strain-engineered nanostructures in MoS₂monolayer investigated by atomic force microscopy

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Controlled modification of two-dimensional (2D) materials' properties is crucial for advanced applications.
• Thermal strain engineering is a key technique for tuning material characteristics.
• Systematic exploration of thermal strain effects on chemical vapor deposition (CVD)-grown MoS2 is lacking.

Purpose of the Study:

• To investigate the strain-induced structure and properties of CVD-grown triangular MoS2 flakes.
• To understand the size-dependent strain behaviors in MoS2 flakes.
• To explore the formation mechanisms of different nanostructures under strain.

Main Methods:

• Advanced atomic force microscopy (AFM) was employed to study MoS2 flakes.
• Experimental analysis of strain distribution and nanostructure formation.
• Correlation of flake size with observed structural modifications.

Main Results:

• Two distinct flake nanostructures, sharp-corner and vein-like, were experimentally observed.
• A critical flake size of approximately 17 μm was identified for the transition between nanostructures.
• Small flakes exhibit strain-modified properties in sharp-corner regions due to large tensile strain.
• Large flakes form vein-like nanoripple structures via interface slipping under tensile strain.

Conclusions:

• MoS2 flake behavior under thermal strain is critically dependent on flake size.
• Size-specific strain engineering leads to distinct nanostructures with unique properties.
• Findings provide insights for designing and preparing strain-engineered nanostructures in 2D materials for device applications.