Kirste, LutzLutzKirsteDanilewsky, A.N.A.N.DanilewskySochacki, T.T.SochackiKöhler, KlausKlausKöhlerZajac, M.M.ZajacKucharski, R.R.KucharskiBockowski, M.M.BockowskiMcNally, P.J.P.J.McNally2022-03-122022-03-122015https://publica.fraunhofer.de/handle/publica/38849110.1149/06601.0093ecstThe defect structure of HVPE-GaN crystals are examined using synchrotron white-beam X-ray topography (SWXRT) and topography results are interpreted and discussed in comparison to reciprocal lattice point broadening from high resolution X-ray diffraction (HRXRD) measurements. Two as-received commercial HVPE-GaN wafers from two different vendors and one HVPEGaN which was grown on an ammonothermal GaN-seed are investigated in this study. From large-area topography the formation of a cellular defect network is identified for the commercial HVPE-GaN. Large differences in the crystal lattice misorientation deformation (mosaicity) are determined for the different samples by transmission section topography. For the HVPE-GaN grown on an ammonothermal GaN-seed a very low defect density was ascertained. From the contrasts of the topography threading screw-type dislocations and threading mixed-type dislocations were identified. The structure analyses show that the outstanding structural properties of the ammo-nothermal GaN-seed are adopted by the HVPE-GaN.en667conference paper