Insertion and diffusion of helium in cubic silicon carbide have been investigated by means of density functional theory. That method has first been assessed by calculating relevant properties for the perfect crystal along with point defect formation energies. Results are consistent with available theoretical as well as experimental data. Helium insertion energies have been calculated to be lower for divacancy and silicon vacancy defects compared to the other mono-vacancies and interstitial sites considered. Migration barriers for helium have been determined by using the nudged elastic band method. Calculated activation energies for migration in and around vacancies (silicon vacancy, carbon vacancy or divacancy) range from 0.6 to 1.0 eV. The activation energy for interstitial migration is calculated to be 2.5 eV. These values are discussed and related to recent experimental activation energies for migration that range from 1.1 to 3.2 eV, depending on the SiC samples used and on helium implantation conditions.
Revised: January 11, 2006 |
Published: January 1, 2006
Citation
Van Ginhoven R.M., A. Chartier, C. Meis, W.J. Weber, and L.R. Corrales. 2006.Theoretical Study of Helium Insertion and Diffusion in 3C-SiC.Journal of Nuclear Materials 348, no. 1-2:51-59.PNNL-SA-41025.