FINE INTERFERENCE EFFECTS IN X-RAY-DIFFRACTION FROM MULTILAYERED STRUCTURES

Attention is drawn to the importance of interference effects in the X- ray diffraction spectra for the precise characterization of multilayer ed structures. A novel simulation procedure, based on direct summation of waves scattered by atomic planes, permits to obtain analytical exp ressions for diffraction spectra and to expose interference contributi ons which are usually hidden within the Takagi-Taupin formalism. The s imulation routine is suitable for the introduction of local variations of the structural and geometrical parameters, such as interface rough ness or defect-induced local fluctuations of interplanar spacing. A ne w interference effect-a strong influence of lattice disorder on the pe riodicity of intensity fringes-was found as a result of the careful an alysis of the diffraction spectrum from a triple-layered structure. Se lected applications of this approach to the study of local lattice dis order in SiGe/Si heterostructures, to the characterization of ultrathi n GaAs/GaInAs/GaAs quantum wells, amorphous SiO2 layers buried in Si, and nearly matched InGaP/GaAs heterostructures, are given. (C) 1998 Pu blished by Elsevier Science S.A.