Topological line defects in hexagonal SiC monolayer

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Two-dimensional (2D) materials offer tunable properties through defect engineering.
• Recent synthesis of 2D silicon carbide (SiC) necessitates understanding defect impacts.
• Extended Line Defects (ELDs) are crucial structural features in 2D materials.

Purpose of the Study:

• Investigate the structural, electronic, and reactivity properties of ELDs in hexagonal SiC.
• Characterize different types of interstitial atom pair ELDs (SiSi-, SiC-, CC-ELD).
• Explore the influence of ELDs on SiC's electronic band structure and chemical reactivity.

Main Methods:

• Density Functional Theory (DFT) for structural and electronic analysis.
• Born-Oppenheimer Molecular Dynamics (MD) for stability assessment.
• Kinetic Monte-Carlo (KMC) simulations for reactivity studies.
• Simulated Scanning Tunneling Microscopy (STM) for defect identification.

Main Results:

• Formation of all studied ELD systems is endothermic; CC-ELD exhibits highest stability at 300 K.
• Simulated STM successfully identified and distinguished between SiSi-, SiC-, and CC-ELDs.
• ELDs introduce mid-gap states, altering the electronic band structure from pristine SiC's direct band gap (2.48 eV).
• ELD regions show significantly enhanced reactivity towards hydrogen adsorption.

Conclusions:

• Defect engineering via ELDs in hexagonal SiC offers a route to tune material properties.
• The identified ELDs impact electronic structure and surface reactivity.
• Findings support potential applications of defect-engineered 2D SiC in catalysis, optoelectronics, and surface science.