Photoluminescence and electron-spin-resonance studies of defects in ion-implanted thermal SiO2 films

Photoluminescence (PL) and electron-spin-resonance (ESR) studies were carried out on thermal SiO2 films after B+ or P+ implantation. Two PL bands at 4.3 eV and 2.6 eV were observed. For the 4.3-eV bands, two PL excitation bands were observed at 5.0 eV and 7.4 eV. Based on the comparison with those observed in oxygen-deficient-type bulk SiO2, the 4.3 eV and 2.5 eV PL bands are ascribed to oxygen vacancies induced by ion implantation. The decay of the 4.3-eV band in ion-implanted thermal SiO2 films follows a power low or stretched exponential, suggesting the distribution of PL lifetime. The ESR signal of the paramagnetic E' centers in ion-implanted thermal SiO2 films were found to be broadened by dipole-dipole interactions between the closely spaced defects. The PL and ESR results suggest that the oxygen vacancies induced by ion implantation in thermal SiO2 films are perturbed by the local network structures.