Quantitative Roughness of Sputtered Fe-Cr Superlattices

We obtained quantitative values of all significant parameters describing the roughness of Fe-Cr superlattices, both in the lateral and growth directions, by statistical analysis of energy-filtered transmission electron microscopy images using cross section samples. These results are in good agreement with the complementary low-angle x-ray scattering measurements. The interface roughness of sputtered Fe–Cr superlattices was changed systematically by varying Ar-pressure during the growth and the number of the bilayers. By scaling local window size we obtained the dependence of the saturated roughness and its correlation lengths in both the lateral and growth directions. The roughness and its correlation lengths (lateral and perpendicular) increase with pressure. However correlation length in the lateral is constant with bilayer index for low-pressure sputtered samples.