We have studied the photoluminescence characteristics associated with the defects produced by Si+ ion-beam mixing of SiO2/ Si/SiO2 films. The photoluminescence peaks show a strong dependence on annealing process before ion-beam mixing. Using electron spin resonance and X-ray photoelectron spectroscopy, the relationship between the photoluminescence peaks and the defects is discussed. (C) 2004 Elsevier B.V. All rights reserved.