Structural state of non-polar a-plane GaN layers grown by MOVPE on r-plane sapphire was investigated by X-ray diffraction method. Interplanar spacings were measured in three directions and corresponding strains were determined. A crystalline perfection was studied by measurement of diffraction peaks of θ- and θ-2θ-scanning in Bragg- and Laue-diffraction geometry. Their FWHM was analyzed by Williamson-Hall plots. Anisotropy of the elastic strains and the peak broadening was revealed. It was shown that a different broadening of diffraction pattern in two in-plane directions was not caused by mosaicity and could be explained by a specific distribution of dislocations.

X-Ray Diffraction Study of Strain and Defect Structure of Nonpolar a-Plane GaN-Layers Grown on r-Plane Sapphire. R.N.Kyutt, M.P.Shcheglov, V.V.Ratnikov, A.E.Kalmykov: Physica Status Solidi A, 2009, 206[8], 1757-60