Study of the 1096.9meV photoluminescent oxygen-related centre in neutron-irradiated CZ-Si:: Formation and structure

The creation process and the structure of an oxygen-associated centre in Si are investigated by means of photoluminescence (PL). The centre is formed after annealing between 250 degrees C; and 450 degrees C in neutron-irradiated CZ-Si and is photoluminescent with a bound exciton emission at 1096.9 meV. We show that this PL line as well as the I1 PL line (1018.2 meV) are the major features of the PL spectra for samples annealed in this temperature range. The comparison of the PL spectra obtained in CZ-Si and FZ-Si crystals indicates that the 1096.9 meV PL line is formed at expenses of Il, thus suggesting the associated centre is presumably created by complexing the trigonal Il centre with one (or more) interstitial oxygen. Uniaxial stress measurements and the observed oxygen isotopic shift (0.037 meV) show that the PL line is associated with an oxygen centre of monoclinic I symmetry. The thermal activation energy of the binding exciton deduced from the intensity decay, Delta E= 5.1 meV, together with the stress behaviour suggest that the centre probably corresponds to an iso-electronic centre.