Results are presented from the photoluminescence properties of C-doped Si-rich thin film oxides implanted with Er, as investigated for various postdeposition implantation and subsequent annealing and passivation conditions. In particular, it was found that the near-infrared Er luminescence intensity can be increased by up to a factor of ∼4 after a postdeposition anneal at temperatures of 300–1100 °C. The postdeposition annealing also resulted in an enhancement of the green-red (500–600 nm) PL band associated with the film matrix. Post-Er implantation passivation in an oxygen atmosphere resulted in a gradual reduction in intensity for both the Er and matrix PLs, and led eventually to a complete quenching of both PLs at the highest passivation temperature (900 °C). In contrast, hydrogen passivation increased the matrix PL intensity by a factor up to ∼2, but was found to have negligible effects on Er PL intensity over a wide range of passivation temperatures. Analysis of Er and matrix-related PL characteristics suggests that the matrix luminescence centers are most likely the sensitizers responsible for energy transfer to Er in C-doped silicon oxides. In this context, a discussion is presented of potential types of matrix-related luminescence centers present in such materials, along with the possible mechanisms leading to differences in Er excitation and deexcitation between the C-doped Si-rich oxide films analyzed herein and commonly reported Si-rich oxide materials containing Si nanocrystals.