Figure 1

(Color online) Structures of the most stable neutral silicon-interstitial configurations. Light gray (yellow) balls represent the Si atoms, whereas dark gray (cyan) balls the carbon atoms. The silicon-interstitial atoms at cubic $\left(k\right)$ and hexagonal $\left(h\right)$ initial positions are labeled.Reuse & Permissions

Figure 2

(Color online) Structures of the metastable ${\mathrm{Si}}_i\text{−}{\mathrm{Si}}_i$ defects. Light gray (yellow) balls represent the Si atoms, whereas dark gray (cyan) balls the carbon atoms. The silicon-interstitial atoms at cubic $\left(k\right)$ and hexagonal $\left(h\right)$ initial positions are labeled. The atoms in the forefront are semitransparent in order not to hide the other atoms behind. The numbers below the figures are the calculated LDA total energy in eV with respect to that of the stablest ${\mathrm{Si}}_i\text{−}{\mathrm{Si}}_i$ defect.Reuse & Permissions

Figure 3

(Color online) Structures of the most stable ${\mathrm{Si}}_i\text{−}{\mathrm{Si}}_i$ defects. Light gray (yellow) balls represent the Si atoms, whereas dark gray (cyan) balls the carbon atoms. The silicon-interstitial atoms at cubic $\left(k\right)$ and hexagonal $\left(h\right)$ initial positions are labeled. The atoms in the forefront are semitransparent in order not to hide the other atoms behind. The corresponding calculated local vibration modes in the phonon gap are shown below. The calculated phonon bands of the perfect crystal is shown in gray. The symmetric modes are marked with arrows. Intensities are related to the phonon density of states and does not involve the excitation probability.Reuse & Permissions

Figure 4

(Color online) Metastable ${\mathrm{Si}}_i\text{−}{\mathrm{C}}_i$ defects. Light gray (yellow) balls represent the Si atoms, whereas dark gray (cyan) balls the carbon atoms. The carbon- and silicon-interstitial atoms at cubic $\left(k\right)$ and hexagonal $\left(h\right)$ initial positions are labeled. The atoms in the forefront are semitransparent in order not to hide the other atoms behind. The numbers below the figures are the calculated LDA total energy in eV with respect to that of the most stable ${\mathrm{Si}}_i\text{−}{\mathrm{C}}_i$ defect.Reuse & Permissions

Figure 5

(Color online) The most stable structure of ${\mathrm{Si}}_i\text{−}{\mathrm{C}}_i$ defect. Light gray (yellow) balls represent the Si atoms, whereas dark gray (cyan) balls the carbon atoms. The carbon- and silicon-interstitial atoms at cubic $\left(k\right)$ and hexagonal $\left(h\right)$ initial positions are labeled. The corresponding calculated local vibration modes in the phonon gap and above the phonon bands are shown in separate panels. The calculated phonon bands of the perfect crystal is shown in gray. Intensities are related to the phonon density of states and does not involve the excitation probability.Reuse & Permissions