With the aim to establish the possibility of synthesis of GaN inclusions by co-implantation of Ga and N ions in silicon and SiO2 films on a silicon substrate, the chemical composition and photoluminescence of implanted layers have been investigated. It is observed that the heavy loss of implanted atoms occurs owing to the out-diffusion (Ga from Si, and Ga and N from SiO2) in the process of post-implantation annealing. Preliminary implantation of nitrogen to form silicon nitride or oxynitride layers is shown to reduce the degree of impurity losses. In the photoluminescence spectrum of both Si and SiO2 subjected to Ga and N co-implantation, the band at 530-550 nm is present, which can be related to 'defect' luminescence of GaN. Copyright © 2017 Inderscience Enterprises Ltd.