Prism coupling as a non destructive tool for optical characterization of (Al,Ga) nitride compounds

An optical characterization technique is proposed for GaN based compounds d eposited on sapphire. In AlGaN films grown by MOCVD, the film optical behav ior and the substrate to layer interface are qualified from the measured op tical data. The experimental and theoretical approach used for this purpose is described in detail. The results clearly show bending effects at the in terface which may be related to structural defects; a good agreement with t ransmission electronic microscopy analysis is obtained.