Determination of the azimuthal orientational spread of GaN films by x-ray diffraction

Sun, Yue Jun; Brandt, Oliver; Liu, Tian Yu; Trampert, Achim; Ploog, Klaus H.; Bläsing, Jürgen; Krost, Alois
December 2002
Applied Physics Letters;12/23/2002, Vol. 81 Issue 26, p4928
Academic Journal
We present a simple but reliable method to determine the azimuthal orientational spread of imperfect epitaxial layers by x-ray diffraction. This method requires the measurement of to-scans in skew geometry from reflections with increasing lattice plane inclination ψ, and a fit of the data by a geometrical model that considers the simultaneous presence of polar and azimuthal orientational spread within the layer. The values thus obtained for various GaN layers grown on SiC are shown to be in good agreement with those measured directly by φ-scans of the ( 1&1macr;00) reflection in grazing incidence, and with those deduced from the edge dislocation densities determined by plan-view transmission electron microscopy.


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