The double heterostructure GaN/InGaN/GaN films with different thicknesses of the InGaN layer were grownat 780℃ or 800℃ by metal organic chemical vapour deposition. The samples were investigated using x-ray diffraction (XRD), room-temperature photoluminescence (PL) and Raman scattering. The dependences of the samples on both the growth temperature and the thickness of the InGaN layer were studied. The comlp, osition of InGaN was determined by the results of XRD, and the bowing parameter of InGaN was calculated in terms of the PL spectra. When the thickness of the InGaN layer was reduced, the phase separation of InGaN was found in some samples. The Raman frequency of the A1 (LO) and E2 (low) modes in all the samples shifted and did not agree with Vegards law.