X-ray diffraction analysis of threading dislocation densities in epitaxial layers as grown by MOCVD

Summary form only given. Threading dislocation densities in epitaxial layers were evaluated using two different X-ray analysis techniques: Williamson Hall (WH) plots and reciprocal space mapping (RSM). The crystalline epitaxial layers were grown by MOCVD. They were composed of columnar structures that can be estimated by coherence length and angular misalignment. The RSM technique, depending on the scanning point, is capable of providing unique information with respect to these columnar structures. On the other hand, a WH plot can provide on overall mean value of the metrics for crystalline structures. Two dominant types (screw and edge) of threading dislocation densities in the epitaxial layers were found by both techniques. The dislocation densities in the epitaxial layers were found to depend strongly on the type and thickness of GaN or AlN nucleation layer.