Photoluminescence study of defects in ion-implanted thermal SiO₂ films

Photoluminescence (PL) study was performed on B or P ion-implanted thermal SiO₂ films. Two PL bands at 4.3 and 2.6 eV were observed. For the 4.3 eV bands, two PL excitation (PLE) bands were observed at 5.0 and 7.4 eV. Based on the close similarities of the PL and PLE bands to those observed in oxygen-deficient-type bulk silica, the 4.3 and 2.6 eV PL bands are ascribed to the oxygen-deficient-type defects induced by ion implantation. While the 4.3 eV PL band in the bulk SiO₂ decays exponentially, the decay of the corresponding PL band in the implanted thermal SiO₂ films follows a power low or stretched exponential, suggesting the distribution of PL lifetimes. This suggests that the oxygen-deficient-type defects induced by the ion implantation in thermal SiO₂ films are perturbed by the structural distribution of the surrounding Si-O-Si network, including the concentration of PL quenching centers.