Published online by Cambridge University Press: 26 February 2011
A new type of bistable center is observed in electron-irradiated Si and identified as an interstitial carbon-substitutional carbon pair by combining several spectroscopic techniques. In the positive and negative charge states, the stable configuration of the defect involves a carbon-silicon interstitialcy (each atom 3-fold coordinated) next to a 4-fold coordinated substitutional C atom. In the neutral state, the defect rearranges its bonds so that both C atoms are substitutional (4-fold coordinated) with a 2- fold coordinated Si atom nestled between. Configurational coordinate energy surfaces are determined for each of the three charge states.