Theoretical study of small silicon clusters in4H−SiC

We have studied the small clusters of silicon and carbon interstitials by ab initio supercell calculations in $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$. We found that silicon interstitials can form stable and electrically active complexes with each other or with a carbon interstitial. Local vibration modes and ionization energies were also calculated in order to help the identification of the defects. We propose that silicon interstitials can emit from these clusters at relatively high temperatures, which may play an important role in the formation of the ${D}_{I}$ center.