Simulations of the initial oxidation process of a SiC surface exposed to O 2 and H 2O molecules was studied with ReaxFF, an atomically detailed reactive molecular dynamics method that naturally models the breaking and forming of bonds. In this work, the ReaxFF forcefield was first expanded by training it with new quantum mechanics data of the binding energy, equation of state, and heat of formation of the SiC crystal, along with data from earlier studies that describes Si - Si, Si - O, and Si - H interactions. This expanded ReaxFF forcefield is capable of simultaneously describing both Si-C-O and Si-O-H bonding interactions. Using the forcefield, oxidation simulations were performed at various temperatures (in the range of 500 to 5000 K), and the trajectories were analyzed. The analyses showed that SiC gradually transforms into the oxides of silicon with simultaneous formation of a graphite-like layer. In presence of excess O 2, the graphite-like layer was further oxidized to CO and CO 2. We also analyzed the trajectories with two-atom and three-atom clusters to quantitatively track the oxidation progress. This analysis clearly showed Si-O and C-C bond formation at the expense of O-O and Si-C bond consumption indicating SiC oxidation with simultaneous formation for carbon-like structure. Consumption of SiC with O 2 was found to be faster than that with H 2O. We have also reported the oxidation simulation of SiC with a mixture of H 2O and O 2. Oxidation proceeded effectively as a two-part sequence, with O 2 first oxidizing the SiC, followed then by H 2O.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films