The photoluminescence properties of silicon rich oxide (SRO) and silicon oxynitride (SNO) films were studied. The materials were obtained by the low pressure chemical vapor deposition (LPCVD) technique, with some samples post- treated by Si-implantation and thermal annealing under different conditions. For SRO films, strong red emission with peak at 1.7 eV was observed after Si-implantation and thermal annealing. The emission intensity depends on the deposition and post-treatment parameters. For SNO films, however, strong blue emission with a peak at 2.38-2.66 eV was observed both in the as-deposited and annealed states. The emission intensity and peak position can be adjusted by thermal annealing. This emission band was also compared with that produced by PECVD-SRO films. The experimental results were explained according to the structural properties of each material. It could be possible that the emission depends not only on Si excess but also on the microstructure of the material.