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 dis location 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, 2 00, 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 diffracto meter. The procedure for fitting calculated values of differential DS to th e experimental data enabled not only the integral characteristics of the st ructure's perfection (Debye-Waller static factor, L-H, and coefficient of e xtinction of radiation due to additional energy losses on defects, (mud) bu t also the average radius, (r) over bar, and concentration, (n) over bar, o f microdefects (precipitates to be obtained).