Extended kinematic approach to the simulation of high-resolution X-ray diffraction spectra. Application to structures with buried amorphous layers

A new approach to the simulation of high-resolution X-ray diffraction spectra utilizing direct summation of waves scattered by atomic planes has been developed. The calculation procedure, in general, is amenable to the introduction of local variations of structural and geometric parameters. For the important structure under consideration here, viz the triple-layered structure with an amorphous layer 'sandwiched' between two crystalline layers having closely matched lattice parameters, account was taken of local fluctuations of the interface thickness and of defect-induced fluctuations of the interplanar spacing. An analytical expression for the diffraction spectrum was derived which allowed a detailed analysis of the characterization problem. As a result, a strong influence of the lattice disorder on the angular periodicity of intensity fringes was found for the first time. Application of this approach to the study of silicon crystals with buried amorphous layers is discussed.