Growth properties of GaPN layer by organometallic vapor phase epitaxy (OMVPE) have been investigated. The effect of growth temperature on the nitrogen contents reveals that the nitrogen content is limited by thermal desorption of nitrogen related species. The desorption energy of nitrogen related species is not dependent on the group-V vapor composition. From the photoluminescence (PL) measurement, post growth annealing in pure nitrogen is effective to improve the PL intensity, but the effects of annealing is slightly different from the samples grown by molecular beam epitaxy. (c) 2006 Elsevier B.V. All rights reserved.