Fig. 4: Defect levels, structures, and modifications of the C_i center.

Structure of a the C_i center, b the displaced “B” configuration of the C_i center, and modified versions of the C_i center with H bonded to either c the carbon, or d the Si atom. Atoms are colored as follows—Si (gray), carbon (black, green), H (red), Si self-interstitial (pink). e Energy level diagrams for the neutral charge state of the C_i center, with conduction band (green), valence band (blue), localized defect levels (red), and electron occupation (black arrows) indicated. Panels on the right show the real space wavefunctions corresponding to each localized defect level.