Characterization of Co/Cu multilayers growth by scanning probe microscopy

Abstract

We have studied the behavior of the growth of Co/Cu multilayers as a function of the Pb buffer layer thickness. Using ex situ scanning force microscope we have measured the topography of the top surface of [Co(10 Å)/Cu(20 Å)] 20 multilayered structure. The samples were thermally evaporated at room temperature onto silicon(1 0 0) covered with Pb buffer layers of different thickness. The surface topography of single buffer layers was measured as well. The quantitative estimate of the surface character of samples has been done using the dynamic-scaling theory. The roughness and the size of the islands have been determined. The dependence of roughness on buffer thickness is similar for both single buffer layer and for multilayers. The roughness increases with the Pb buffer thickness, except that of d Pb=300 Å. It has been also observed that the average size of islands increases with increasing Pb thickness. This growth instability could be attributed to the step barrier which resists step-down diffusion of deposited atoms, typical for metals exhibiting Ehrlich–Schwoebel barrier.