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Phys. Rev. B 45, 9292–9310 (1992)

[Issue 16 – 15 April 1992 ]

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Structural refinement of superlattices from x-ray diffraction

Eric E. Fullerton and Ivan K. Schuller
Physics Department 0319, University of California-San Diego, La Jolla, California 92093
H. Vanderstraeten and Y. Bruynseraede
Laboratorium voor Vaste Stof-Fysika en Magnetisme, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium
Received 17 May 1991

We present a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, we derived a general kinematical diffraction formula that includes random, continuous, and discrete fluctuations from the average structure. We show that only the structure factor of one single layer of each material has to be averaged over the random variables and prove that this relation is equivalent to earlier, less general models. Implementing a nonlinear-fitting algorithm to fit the entire x-ray-diffraction profile, refined parameters that describe the average superlattice structure and deviations from this average are obtained. We compare the results of structural refinement to results obtained independently from other measurements. The roughness introduced artificially during growth in Mo/Ni and Nb/Cu superlattices is accurately reproduced by the refinement. The lattice parameters of Ag/Mn obtained from this refinement procedure are in very good agreement with the values obtained from independent extended x-ray-absorption fine-structure and x-ray photoelectron diffraction studies. The relative thicknesses of the layers can be accurately determined, as proved for Cu/Ni in comparison with chemical analysis, for W/Ni compared to the calibrated sputtering rate, and for Mo/Ni compared to the low-angle profile.

©1992 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v45/p9292
DOI: 10.1103/PhysRevB.45.9292
PACS: 68.65.+g, 68.55.Jk, 61.10.My

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References

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