Interface roughness in Ni/Ti multilayers as probed by neutrons

The development of interface roughness in reactively sputtered Ni/Ti multil ayers is investigated by neutron reflectivity measurements. The reflectivit y data of supermirrors show that the interface roughness of the layers is c onsiderably reduced by reactive sputtering. But the degree of interdiffusio n appears to remain the same. Samples prepared at various partial pressures of air clearly demonstrate that a minimum partial pressure of air is suffi cient to obtain smooth interfaces. A drastic decrease of the reflectivity w ith increasing substrate roughness is observed indicating that the reactive sputtering is not sufficient to smoothen the layers that are grown on roug h substrates. (C) 2000 Elsevier Science B.V. All rights reserved.