(589c) Carbon in Liquid Silicon: Diffusion, Solubility, and Silicon-Carbide Nucleation
- Conference: AIChE Annual Meeting
- Year: 2018
- Proceeding: 2018 AIChE Annual Meeting
- Group: Engineering Sciences and Fundamentals
- Time: Wednesday, October 31, 2018 - 4:20pm-4:40pm
Here, we employ an array of atomistic simulation tools to study the properties of carbon impurity atoms and the nucleation of SiC precipitates in liquid silicon. Given the relative paucity of atomistic simulation studies of the liquid silicon-carbon system, we consider multiple empirical potentials including different parameterizations of the popular Tersoff  potential: tersoff-1989 , tersoff-1994 , and Erhart-Albe  (EA), as well as the modified embedded atom method (MEAM)  potential. Using these potentials we compute several key thermodynamic and kinetic properties including carbon diffusivities, solubility limits, liquid-solid segregation coefficients, and homogeneous nucleation barriers for SiC crystallite formation.
We find that most of the potentials give a consistent description of carbon diffusion and melt-solid segregation, and provide predictions that are in line with experimental estimates . However, larger deviations are observed for carbon solubility in liquid silicon; this thermodynamic property is substantially overestimated by all the potentials considered. Some possible reasons for this finding are discussed. Nonetheless, we use the derived solubilities to compute SiC nucleation barriers at known values of carbon supersaturation and undercooling. The results are discussed in the context of experimentally observed SiC particle distributions.
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