InxAl1‐xN (0001) wurtzite layers with 0.2 < x < 0.9 that are grown by molecular beam epitaxy on AlN/Al2O3 templates are studied using Raman spectroscopy. In the high‐frequency part of the spectra (450‐850 cm‐1), the two EH2 modes (one AlN‐ and one InN‐like) and one A1(LO) are observed in the backscattering geometry. The three peaks shift towards higher frequencies as the Al concentration increases. In the low‐ frequency part, three peaks are also observed. The InN‐like EL2 mode is present in the whole composition range while the AlN‐like EL2 mode appears for x > 0.45. In the case of the Al rich samples, an additional broad feature appears. The Raman spectra are fitted using the spatial correlation model providing the extent of the phonon confinement imposed by the alloy potential fluctuations is estimated. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)