Localized destructive interference in X-ray specular reflectivity

Localized destructive interference can be obtained for specific values of t he angle of incidence when studying semiconductor superlattices with X-ray reflectivity at fixed wavelength. Kinematical calculations show that the di fference between the real parts of the refractive index of the layers must be small, and that the number of superlattice periods must be optimized to enhance the destructive interference. An experimental example, involving a CdTe/CdZnTe superlattice, and optical matrix simulations for SiGe/Si superl attices are presented to illustrate this effect. Finally, it is shown that such structures can be tailored to act as energy filters at fixed angles of incidence.