Synchrotron-radiation plane-wave topography

The extremely parallel and monochromatic beam (divergence approximately 0.3'', spectral width Δ lambda/lambdaapproximately7x10-6) extracted from the white synchrotron-radiation X-ray beam by a multiple reflection single-crystal monochromator has been used to record plane-wave reflection topographs. Separate images of a quaternary epilayer, Gasub(0.7)Alsub(0.3)Assub(1-y)Psub(y) and GaAs substrate building up a nearly matched heterostructure have been obtained. Typical thin-crystal features are observed in the epilayer. Differences in the interface dislocation contrast and strain field are revealed between the layer and substrate. By increasing the local departure from Bragg incidence (weak-beam condition), images as narrow as 1 μm can be obtained. (author)