First Principles Investigations on the Carbon‐Related Defects in Silicon

Defect identification for unintentionally induced defects and radiation‐implemented defects always attracts great attention in semiconductor materials. Recent advances in carbon‐implemented single‐photon emitters in silicon urgently require the accurate identification of defect structures to reveal transition mechanisms. Using hybrid functional with finite size correction, we investigate the charge and optical transitions of carbon‐related defects, including CSiCSi, VSiCSi, CSi, SiiCSiCSi, and Ci. Except for Ci, other defects present the negative‐U feature in the charge transition process. CSiCSi and VSiCSi tend to perform p‐type conductivity with the electron capture transition close to the valence band, of which transition level ε (0/−1) is 0.30 eV for CSiCSi and ε (+1/−2) is 0.34 eV for VSiCSi. CSi and SiiCSiCSi present a bipolar doping character, and CSi tends to capture holes with transition ε (0/+2) = 0.10 eV. The optical transitions that typically emit or absorb light in the telecom optical wavelength bands are identified in these defects in terms of band edge recombination. The zero‐phonon lines of optical transitions of ε (+2/+1) for VSiCSi and Ci are consistent with a previous experiment involving single‐photon emitters. The findings are helpful to understand the performance degradation of silicon devices and provide a reference for identifying the structure of carbon‐related defects in silicon.