New method for the in situ determination of Al_xGa_(1-x)N composition in MOVPE by real-time optical reflectance

摘要

This paper reports on the in situ determination of the Al-content in Al_xGa_(1-x)N layers deposited by MOVPE on sapphire and silicon substrates by means of optical reflectance. The accuracy of the conventional in situ method which utilizes the dependence of the refractive index and the extinction coefficient on Al-content is compared to that of the new dispersion approach. The limits and possibilities of the new approach will be discussed.