Résumé
We report on the structural properties of GaN layers deposited by atmospheric pressure MOVPE on sapphire substrates. Using both Raman and spatially resolved micro-Raman spectroscopy, we show that they have almost no strain and a negligeable concentration of residual free carriers. In some samples, we evidence also a high level of interfacial disorder which varies from run to run. This comes from the experimental difficulty to fully master the GaN buffer layer morphology.