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 (CuKalpha1 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, (mud) but also the average radius, (r) over bar, and concentration, (n) over bar, of microdefects (precipitates to be obtained).