CONVERGENT-BEAM ELECTRON-DIFFRACTION AND X-RAY-DIFFRACTION CHARACTERIZATION OF STRAINED-LAYER SUPERLATTICES

The diffraction amplitude of a reflection of a strained-layer superlattice is given explicitly in terms of the strains and thicknesses of the superlattice bilayer using the kinematical theory of electron diffraction. A tension-compression step model of the superlattice is used. This expression which is equivalent to a similar expression given by Segmuller and Blakeslee for X-ray diffraction (XRD) provides insight into the diffraction of superlattices. Superlattice sidebands or peaks in the rocking curves of convergent-beam electron diffraction (CBED) and double-crystal XRD can be inferred and explained. The good match between calculated profiles and experimental profiles of a GexSi1-x/Si superlattice is given as an illustration.