Raman and micro-Raman spectroscopy of GaN layers deposited on sapphire

摘要

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.