COHERENCY OF INTERFACIAL ROUGHNESS IN GAAS/ALAS SUPERLATTICES

The presence of a nonrandom fractional number of atomic planes in each layer of a superlattice produces unusual diffraction patterns in which the peaks cannot be indexed in the usual fashion as due to a single series. The x-ray line broadenings are distinctly different from earlier measurements and calculations in which the interfacial roughness is due to random variations of the scattering function. Therefore, interfacial roughness encountered at a single interface may just be a consequence of controlled, but not random, roughness and that under proper growth conditions superlattices with atomically sharp interfaces may be produced. These results are in good agreement with experimental measurements. © 1990 The American Physical Society.