ISSN:
1063-7834
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Two-and three-crystal diffractometric study of the structural perfection of GaN epitaxial films grown on sapphire, GaAs, and SiC substrates is reported. The diffraction intensity distributions around the reciprocal-lattice points are shown to be extended in the direction parallel to the surface, which is connected with the anisotropy of the local strain fields in the layers. A comprehensive analysis is made of the broadening for several reflection orders measured in three geometries, namely, Bragg, symmetric Laue, and grazing-angle diffraction. The five independent components of the microdistorsion tensor δe ij , as well as the average coherent-scattering lengths in two directions, τ z and τ x , have been obtained. It is shown that for most samples the components responsible for reflection broadening along the surface are noticeably larger, i.e. δe xx 〉δe zz , and δe zx 〉δe xz , as well as τ z 〉τ x . All tensor components are related to a specific dislocation type. Electron microscopy of the samples revealed a high density of pure edge and pure screw dislocations extending normal to the interface, and which provide a dominant contribution to e xx and e zx , respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1134/1.1130722
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