Calculation of two-dimensional maps of diffuse scattering by a real crystal with microdefects and comparison of results obtained from three-crystal diffractometry

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, , and concentration, , of microdefects (precipitates to be obtained).