Bragg and Laue x-ray diffraction study of dislocations in thick hydride vapor phase epitaxy GaN films

The dislocation structure of hydride vapor phase epitaxial thick GaN layers grown on sapphire is studied by analysis of the microdistortion tensor com ponents. Symmetrical reflections (including reflections from planes forming a large angle with the basal plane) with two modes of scanning (theta and theta -2 theta) in two geometries (Bragg and Laue) are used to obtain the t ensor components. The instant connections between the tensor components and major dislocation types are specified. Different types of dislocation dist ributions have been identified in the thick GaN films grown on sapphire wit h and without undoped and Si-doped metalorganic chemical vapor deposited te mplates. Transmission electron microscopy was used to confirm the x-ray res ults by direct visualization of defect rearrangements. (C) 2000 American In stitute of Physics. [S0021-8979(00)06023-0].