Wt present the results of GaN characteristics affected by the strain field existing in the Si(1 1 1) substrate, which was implanted with 60 and 1009 keV nitrogen ions (N+) to a dose ranging from 2 x 10(14) to 2 x 10(16) cm(-2) prior to the film growth. GaN epitaxial films were grown on GaN/AlN-buffered and AlN-buffered implanted-substrates, respectively, by the metalorganic chemical vapor deposition technique. They were investigated by Raman scattering and photoluminescence. In the case of GaN film with the single-buffered layer, the tensile stress in the film decreased as the stress in the substrate increased. In contrast, the properties of the GaN films with the double-buffered layers made little difference regardless of the magnitude of stress in the substrate. It can be concluded that the implanted layer in substrate contributes to relax the stress that is generated in film and then to make better optical property of GaN film.