TheSiO2layers thermally grown on Si wafers were implanted by 130 keV Si ions at liquid nitrogen temperature to a dose of1×1017 ions/cm2.From the as-implanted samples, a visible photoluminescence band centered around 2.0 eV was observed. After postannealing at 1100 °C for 90 min another visible band in the range of 1.7 eV was detected. Interestingly, with increasing thermal annealing time, a blue shift in peak energy and an intensity variation of the 1.7 eV band were observed. A possible interpretation for the observations was discussed in terms of a so-called three-region model. ©1997 American Institute of Physics.