The Behaviour of Surfactants during the Growth of Co/Cu Multilayers

Abstract

The [Co(1 nm)/Cu(2 nm)]N multilayers with different numbers of bilayer repetitions (N = 3 and 10) were thermally evaporated on Si(100) substrates with a small amount of Bi or Pb deposited only on the first and on the second Cu layer. The chemical composition of the surface after each step of the preparation process was studied by Auger electron spectroscopy. The evolution of the Auger peaks showed the segregation of Bi and Pb surfactants. During the evaporation of the subsequent Co and Cu layers, gradual decrease in the surfactant amount on the surface was observed. No appearance of Co peak on the Cu layer, and Cu peak on the Co layer even for a coverage of a few A indicates the layer continuity. The interface roughness of the surfactant-mediated Co/Cu layers analyzed by X-ray reflectometry (when surfactant was deposited twice) was similar to the pure Co/Cu samples. However, more repetitions of surfactant, by reduction of interface roughness, improve the layer quality.