A strict dynamical theory of radiation scattering in defect crystals is developed involving no arbitrary assumptions. Final theoretical expressions are obtained for the case of Laue‐diffraction in monocrystals containing homogeneously distributed defects, in particular Coulomb‐like defects (clusters, dislocation loops). The theory gives an unified description of the thickness dependences of intensity scattering both, for thin and thick crystals, and predicts an effect of anomalous transmission of diffuse background in thick crystals. Experimental investigations on O‐ or Cu‐doped Si‐monocrystals are carried out which confirms the theory.

Two-dimensional maps of x-ray diffuse scattering (DS) in a reciprocal space for a real crystal containing Coulomb deformation centres (clusters or dislocation loops) were calculated using a new dynamical theory developed for a crystalline media with homogeneously distributed defects. Such maps were calculated for both the fundamental, 400, as well as the quasi-forbidden, 200, reflections of x-rays (CuKα 1 radiation) for a binary crystal (GaAs). They were also discovered experimentally in the GaAs films heavily doped with Si (up to 10 20 cm −3) by means of a Philips three-crystal diffractometer. The procedure for fitting calculated values of differential DS to the experimental data enabled not only the integral characteristics of the structure's perfection (Debye-Waller static factor, L H , and coefficient of extinction of radiation due to additional energy losses on defects, µ d) but also the average radius,r, and concentration,n, of microdefects (precipitates to be obtained).

One of the important subjects in the material science of semiconductor compounds is a problem of stoichiometry. The methods based on the measurement of kinematical integral reflectivity (IR) , R. , for the quasi-forbidden reflection (QFR) of X-rays were formerly used for investigation of the GaAs composition. To determine the value of deviation from stoichiomerry, A =C A-C B where C t is a concentration of the component A or B, one should make some corrections for extinction phenomena which is difficult to take into account for a real (with defects) crystal. The reflectivity of a real crystal for a QFR, R t , may be also described within the dynamical theory taking into account the Debye-Waller static factor , L H , the extinction coefficient (ii ds , and parameter A. To determine these characteristics the experimental thickness pendulum oscillation of Rf (t) (200 reflection, A,=0.1198nm) was measured and analysed for the first time. By this the Honl corrections of atomic formfactors for anomalous dispersion were made. Another independent approach consisted in analysis of the experimental energetic dependence of the R.(A) for the wavelengths situated between the two absorption K-edges was used too. Relatively close values of the L H and (ii ds for GaAs crystals with dislocations as well as parameter A were obtained by fitting of the R. (/) and R t (A) nonlinear functions, calculated by the theory , to the experimental data.

Bragg and diffuse scattering contributions to a reflection can be separated using the intensity dependence on the amplitude of transverse ultrasound excited in the crystal. The method is based on the fact that a weak ultrasound with wavelength equal to the extinction length suppresses almost completely the anomalous transmission of the coherent (Bragg) beam in a sufficiently thick absorbing crystal and does not affect diffuse scattering. Both parameters characterizing diffraction in a slightly imperfect crystal, the static Debye-Waller factor and the coefficient of additional absorption due to diffuse scattering, have been determined for a silicon crystal containing oxide precipitates after heat treatment.

The amplitude dependences of the integral reflectivity (IR) Ri(W) of perfect silicon crystals distorted by shear short wave ultrasonic vibrations are investigated for high order reflections of AgKβ, AgKα1 radiations. Transition to the kinematical regime of diffraction is obtained for high ultrasound amplitudes both, in the Laue and in the Bragg case of diffraction. The ratios of the integral reflectivities measured in the initial and distorted state of a crystal are in agreement with the theory developed formerly. The influence of structural defects on the transition of the IR to the kinematical regime is studied, too.