X‐ray multiple diffraction as a new approach to structural characterization of III‐nitride layers

X-ray multiple diffraction in epitaxial films of III-nitrides has been studied. A series of single layers of GaN, AlN, AlGaN and superlattices AlGaN/GaN of different thickness and structural perfection grown on c-sapphire are under study. Renninger scans for a primary forbidden 0001 reflection was used. The three beam diffraction peaks were measured in both φ-scans and θ-scans and their FWHM was analyzed. In the Renninger pattern all the possible 10 multiple peaks in an angular range (0–30)° are observed. It is shown that the FWHM of the φ-peaks reflects a crystalline perfection level but does not depend markedly on the multiple combination type. The angular width of the θ-scan peaks also increases with increasing of dislocation density and strongly depends on the type of three-wave reflection. The combinations with pure Laue secondary reflection (1–100)/(–1101), (3–1–20)/(–3121) and (3–2–10)/(–3211) are most sensi-tive to the dislocations. Most narrow peaks for the samples with the large dislocation density take place for the multiple combination (01–13)/(0–11–2) with the largest Bragg component of the diffraction vector. For the superlattices, θ–2θ-scan curve measured in the multiple position on the φ-scale contains satellites with angular distance corresponding to the forbidden 0001 reflection. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)