Phosphorus-divacancy complexes in irradiated silicon

Reconstruction processes proceeding during annealing of radiation defects in 60Co γ-ray-irradiated (Tsub(irr) < approx. 500C) n-type silicon (ρ=20 to 250 Ω cm) grown by the vacuum flat-zone technique were investigated. The temperature dependences (80 to 400 K) of charge carrier concentration and life time were measured at various stages of annealing (Tsub(ann) = 100 to 6000C). It has been established that during annealing the E-centres interact with carbon-containing complexes of an interstitial type or are transformed into more complicated complexes of phosphorus-divacancy. Phosphorus electrical activity is completely restored after annealing of phosphorus-divacancy complexes at Tsub(ann) = 400 to 5000C. The energy level of phosphorus-divacancy complexes was found to be in the lower half of the forbidden gap (ΔEsub(r) = 0.34 eV). The cross-section σsub(p) for hole capture by these complexes was found to be 4 x 10-15 cm2. It was concluded that the phosphorus-divacancy complexes are singly charged acceptors. (author)