Dl. Abernathy et al., 1D X-RAY SPECKLE PATTERNS - A NOVEL PROBE OF INTERFACIAL DISORDER IN SEMICONDUCTOR SUPERLATTICES, Solid-state electronics, 40(1-8), 1996, pp. 531-535
The high brilliance of third generation undulator sources offers an un
precedented opportunity to perform coherent X-ray diffraction studies
of the structure and dynamics of materials on length scales down to in
teratomic spacings. We have measured the coherent diffraction or ''spe
ckle'' pattern from a GaAs/AlAs superlattice. The speckle diffraction
is consistent with height fluctuations of the superlattice of similar
to 10 Angstrom over lengths of order 60 mu m. Unlike other methods of
characterizing the roughness of semiconductor material, such as scanni
ng probe microscopies (STM, AFM) or scanning electron microscopy (SEM)
, this novel coherent diffraction method is sensitive to lateral varia
tions of the interface height buried within the small illuminated volu
me of the material, and thus can offer information unavailable from ot
her non-destructive techniques.