Twin-Boundary Reduced Surface Diffusion on Electrically Stressed Copper Nanowires

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Surface diffusion significantly influences material phase transformation and structural evolution.
• Understanding surface diffusion is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the evolution of copper nanowires under electric-current driven surface diffusion.
• To elucidate the role of nanoscale defects, specifically coherent twin boundaries (CTBs), in this process.

Main Methods:

• In situ transmission electron microscopy (TEM) for real-time observation of copper nanowire evolution.
• Density functional theory (DFT) computations to determine energy barriers for atomic migration.

Main Results:

• Copper nanowires with dense CTB defects adopted a stable zigzag configuration.
• CTB-intercepted concave triple junctions significantly hindered surface diffusion, reducing diffusivity by nearly one order of magnitude.
• DFT calculations confirmed energy barriers for atomic migration at junctions and faceted surfaces.

Conclusions:

• The stable zigzag surface morphology results from a combination of high-diffusivity facets and stalled diffusion at concave junctions.
• Defect engineering, specifically utilizing CTBs, can control surface diffusion and mitigate electromigration failures.
• This research offers a pathway for developing robust interconnect materials for nanoelectronic devices.