Maksymenko Z. Resonant X-ray diffractometry near K-edges of absorption of components in studies of multilayer systems

The dissertation presents the results of research of singularities of X-ray diffraction for the interval of wavelengths in the region of the K-edges of absorption of components of binary compounds containing structural defects and stoichiometric disturbances using quasi-forbidden reflexes (QFR). In particular, it was found that in the binary crystals with close numbers of atoms of sublattice for the wavelengths near the K-edges of absorption of components for the QFR there are dynamic effects of scattering of X-rays. Simultaneous use of structural and quasi-forbidden reflexes makes it possible to correctly determine both the characteristics of defects and the parameters of non-stoichiometry. For the wavelengths of the waves located between the two K-edges of the absorption com-component, where the actual part of the structural factor for the guise- forbidden (QF) of binary crystals is equal to zero, it is established that the integral reflectivity ability (IRA) is determined only by the magnitude of its imaginary part. It is established that in the Bragg-diffraction geometry there exists a minimum in the energy dependence of the electromagnetic spectrum, which is caused by the closure of the real part of the coefficient of the Fourier decomposition of the polarization of the crystal. The nature of the change in the position of the minimum intensity of intensity in the wavelength region near the K-edges of the absorption of components is determined by the deviation from the stoichiometry, which affects the magnitude of the structural factor. On the basis of comparison of the experimental and theoretical dependences of (IRA) for guise-forbidden reflexes (QFR) and their minima, the degree of non-stoichiometry, as well as the characteristics of microdefects in binary crystals, can be determined. It is shown that in real crystals and film structures with strong absorption, the contribution of the diffusive component to the total reflectivity when using QFR is quite substantial and should be taken into account for the correct determination of the defect parameter. The basis of the non-destructive X-ray diffraction method of control-role of non-stoichiometry of binary crystals at the level of ~10-5, as well as the characteristics of microdefects (size, concentration), was developed. The basis of this method is the measurement of the energy dependences of the IRA for the QFR and the structural reflexes in the minimization of IRA. X-ray diffraction methods have determined the deformation state of short-coperiod AlxGa1−xN / GaN superlattices, as well as the period and thickness of its layers and the composition of the solid solution. Structures grown with a low ratio of III / V component flows have been found to have a greater degree of atomic long-range forging. It is established that the level of deformation in the NG period depends on the ratio of the pit-barrier thicknesses. It is shown that the growth rates of individual layers depend to a large extent on the deformation state of the system - as the stress increases, the growth rate of the barrier layer increases