First principles calculations for iodine atom diffusion in SiC with point defects.

The formation energies, diffusion barriers, vibration frequencies of complex iodine defects in 3C-SiC are calculated. The effective diffusion rates of these complex defects are evaluated in the temperature range from 300 K to 2000 K. The iodine interstitial diffusion is the dominant diffusion mechanism in bulk SiC since its diffusion energy barriers is the lowest. On the contrary, if the iodine atom substitutes a Si or a C atom, the diffusion rate is the lowest. The diffusion rates of other iodine point defects coupled with vacancies are between the rates of these two cases. The vacancies near the iodine atoms are traps for the iodine and they can slow down the diffusion rate of iodine atoms. The experimental diffusion rate of iodine in SiC is between that of calculated interstitial and substitutional iodine. It may result that the experimental data is from the combination of all the point defect diffusion mechanisms. [ABSTRACT FROM AUTHOR]