The methods of 2- and 3-crystal X-ray diffractometry were used to study the dislocation structures of thick layers which were grown via chloride gas-phase epitaxy onto sapphire, or a thin GaN layer, which was grown using metal-organic synthesis. Five components of the micro-distortion tensor, and the sizes of the coherent scattering regions along the sample surface and along the normal to it, were deduced from measurements of the diffracted intensity in the Bragg and Laue geometries. These quantities were used to analyze the type and geometry of the dislocation arrangements and to calculate the number density of the main dislocation types. The density of vertical screw dislocations, as well as of edge dislocations, decreased by a factor of 1.5 to 3 during growth on a thin GaN layer.

X-Ray Measurement of a Micro-Distortion Tensor and its Application to an Analysis of the Dislocation Structure of Thick GaN Layers Obtained by Hydrochloride Gaseous-Phase Epitaxy. V.V.Ratnikov, R.N.Kyutt, T.V.Shubina: Fizika Tverdogo Tela, 2000, 42[12], 2140-6 (Physics of the Solid State, 2000, 42[12], 2240-10)