Tilt Grain Boundary Topology Induced by Substrate Topography

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) crystals possess diverse properties but suffer from random defect formation during synthesis.
• Controlling defects is crucial for tailoring the electronic, mechanical, catalytic, and optical properties of 2D materials.

Purpose of the Study:

• To investigate the use of nonplanar, curved-topography substrates for the intentional and controllable creation of topological defects in 2D materials.
• To develop a theoretical framework and experimental validation for defect engineering on curved surfaces.

Main Methods:

• Augmented phase-field modeling incorporating a geometric phase to track crystal misorientation on curved surfaces.
• Experimental synthesis of tungsten disulfide (WS₂) on silicon templates with controlled topography.
• Theoretical analysis and simulation of crystal growth on conical-planar substrates.

Main Results:

• Demonstrated that curved substrates enable intentional and controllable topological defect formation in 2D materials.
• Successfully predicted and observed grain boundary formation when a growing crystal self-intersects on a curved surface.
• Achieved satisfactory agreement between theoretical predictions and experimental results for WS₂ synthesis.

Conclusions:

• Nonplanar substrates offer a novel pathway for precise control over defect engineering in 2D materials.
• The developed theoretical approach accurately predicts defect formation on curved surfaces.
• This work paves the way for designing 2D materials with tailored properties through controlled defect synthesis.