Depth Resolved X-ray Scattering Topography for gallium nitride epitaxial layer on gallium arsenide substrate

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X-ray scattering topography, which we proposed, has been successliMly applied to lattice-mismatched heteroepitaxial layer system, such as a molecular beam epitaxy grown on InAs on GaAs, metal-organic chemical vapor deposition grown GaAs on Si etc. This method applied any kind of materials, too, arid observed an orientation distribution of an Fe-3%Si single crystal, the structure of the welded region of Al-4%Cu polyciystals, and an amorphous rubber type (composite material). We aimed to obtain depthresolved X-ray scattering topography of GaN on GaAs. We prepared, in order to reach the aim, (1) computer simulation ofX-ray wave field by dynamical diffraction theory, (2) structural study of GaN on GaAs, (3) rebuilding of new measurement system.We have performed computer simulation for lattice mismatched heteroepitaxial layer by dynamical diffraction theory, it was indicated that epitaxial film calculation results are very different from bulk ones.We have measured extremely small angle X-ray diffraction for GaN on GaAs, in order to study depth-depend crystal structure about polymorphism, wurtzite and zinc-blend. Although depth-depend crystal structure was observed, the results were not be able to explain from symmetry. Therefore, we studied structural analysis of this system by measuring reciprocal mapping. In the film wurtzite was inclined to only one [lll] direction, we obtained exact value of deformed lattice constants.We built a new system including CCD camera. Near future, we will obtain a higher spatial resolution topography using a plane wave micro-beam, which were made by asymmetric diffraction monochromator and Synchrotron Radiation.