X‐ray diffraction analysis of structural defects in a‐plane GaN grown on r‐plane sapphire by MOCVD

Abstract

In this work, we demonstrate the use of X‐ray diffraction for analyzing structural imperfections in a‐plane GaN grown on r‐plane sapphire. Although there are only two (hh 0) planes accessible under symmetric diffraction, there are an adequate number of diffraction planes accessible under the quasi‐symmetric configuration to enable analysis of rocking curves that are not influenced by basal‐plane stacking faults. By measuring diffraction profiles for a series of symmetric and asymmetric crystal planes, the broadening terms were separated using extrapolation methods based on their geometric dependence. Individual broadening factors can then be correlated to the relative contribution of different structural defects, including threading dislocations, lateral coherence length, and basal plane stacking faults. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)