Theoretical study of the CiOi and IsiCiOi defects in Si

The ISiCiOi (C4) defect consists of a Si self-interstitial trapped at the interstitial carbon-oxygen CiOi pair (C3). The C4 defect is characterized by two infrared absorption lines at 940 and 1024 cm−1. The former is C-related and the latter is O-related. The intensity of these lines begins to drop above 150 °C and they disappear around 200 °C. In this work, we present the results of first-principles calculations of the configurations, binding energies, vibrational spectra, and estimated gap levels of C3 and C4.