Fine interference effects in X-ray diffraction from multilayered structures

Abstract

Attention is drawn to the importance of interference effects in the X-ray diffraction spectra for the precise characterization of multilayered structures. A novel simulation procedure, based on direct summation of waves scattered by atomic planes, permits to obtain analytical expressions for diffraction spectra and to expose interference contributions which are usually hidden within the Takagi–Taupin formalism. The simulation routine is suitable for the introduction of local variations of the structural and geometrical parameters, such as interface roughness or defect-induced local fluctuations of interplanar spacing. A new interference effect—a strong influence of lattice disorder on the periodicity of intensity fringes—was found as a result of the careful analysis of the diffraction spectrum from a triple-layered structure. Selected applications of this approach to the study of local lattice disorder in SiGe/Si heterostructures, to the characterization of ultrathin GaAs/GaInAs/GaAs quantum wells, amorphous SiO 2 layers buried in Si, and nearly matched InGaP/GaAs heterostructures, are given.