Studying defect structure of GaN epilayers by means of three-beam X-ray diffraction analysis

X-ray multiple diffraction in epitaxial films of GaN with various densities of dislocations has been measured using Renninger scans for a primary forbidden (0001) reflection. The angular widths of three-beam diffraction peaks measured in both φ scans (rotation about the normal to the sample surface) and θ scans (rotation about the Bragg angle) have been analyzed. It is established that the three-beam Renninger diffraction peaks exhibit splitting due to a large-block structure of epilayers. For some three-beam combinations, the half-width (FWHM) of θ scan peaks is highly sensitive to the dislocation density.