N_2iO - The dominant N-O defect in silicon

  In N and O implanted FZ-Si [173], or in Cz-Si grown in a N₂ atmosphere [174,175], NNO complexes are formed by annealing between 400 and 700$^\circ$C. Under these conditions, the intensity of the localised vibrational modes (LVMs) due to the N-pair are progressively reduced and three other IR-absorption lines at 1026, 996 and 801 cm^-1 (room temperature) become increasingly prominent. The intensities of these lines are correlated with each other [175] and they are believed to be due to NNO complexes. This is because O_i atoms become mobile around 400$^\circ$C and become trapped by N-pair defects which are stable at this temperature. Beyond $\approx 700^\circ$C these complexes break up with the emission of O_i leaving the N-pair. Cooling allows the NNO complexes to reform. This dissociation and reformation is reversible.