Bistable defect in silicon: The interstitial-carbon–substitutional-carbon pair

By combining several spectroscopic techniques, we have observed a new type of bistable center in electron-irradiated silicon and have identified it as an interstitial-carbon--substitutional-carbon pair. The positive and negative charge states of the defect share a common stable configuration which differs from that for the neutral state by a simple molecular bond rearrangement. Detailed structural models and configurational-coordinate energy surfaces are presented for each of the three charge states.