Development of the ReaxFF Reactive Force Field for Inherent Point Defects in the Si/Silica System.

Area of Science:

• Computational Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Accurate simulation of atomic interactions is crucial for understanding material properties.
• Existing force fields struggle to precisely model oxygen diffusion and defect behavior in silicon at high temperatures.
• Molecular dynamics (MD) simulations require reliable force fields for accurate predictions.

Purpose of the Study:

• To redevelop ReaxFF force field parameters for Si/O/H interactions.
• To enable accurate MD simulations of Si/SiO2 interfaces and oxygen diffusion in silicon.
• To investigate point defect stability and migration mechanisms in silicon.

Main Methods:

• Developed and trained a new ReaxFF force field (ReaxFF_present) using a quantum mechanical-based dataset.
• Performed MD simulations to study oxygen diffusion mechanisms and barriers in bulk silicon.
• Validated the force field by simulating amorphous SiO2/Si interfaces and annealing processes.

Main Results:

• ReaxFF_present correctly describes oxygen migration in silicon via bond-centered site hopping.
• Predicted oxygen interstitial diffusion barrier in silicon is 64.8 kcal/mol, matching literature values.
• Simulations show oxygen diffusion initiates above 1400 K, with accurate diffusion coefficients.
• The new force field successfully models amorphous SiO2/Si interfaces, overcoming previous simulation limitations.

Conclusions:

• The developed ReaxFF_present force field accurately captures oxygen diffusion mechanisms and barriers in silicon.
• This advancement enables reliable MD simulations of Si/SiO2 interfaces and high-temperature phenomena.
• The new force field overcomes limitations of previous models, improving the study of defect behavior.