Ag as a surfactant for Co/MgO(111)-( 3 × 3 )R 30

Ag was examined as a potential surfactant to aid in the growth of smooth Co films deposited on MgO. Ag was deposited onto single-crystal MgO(111)-( 3 × 3 )R30° substrates. It was found that Ag formed islands upon annealing. Monolayer films of Co were subsequently deposited using an electrostatic electron-beam evaporator on single-crystal MgO(111)-( 3 × 3 )R30° substrates with 0.5–10 monolayers of Ag. The Ag/MgO substrates were held at room temperature or 450 °C during growth, with subsequent annealing of temperatures 400–800 °C. These films have been characterized using low-energy electron diffraction, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Despite the fact that Ag formed islands, it was found that the presence of Ag did have a surfactant effect upon the thin-film growth of Co on Ag/MgO(111)-( 3 × 3 )R30°. Co islands were still present, but the surface was much smoother than for films grown without the Ag surfactant. XPS peak intensity changes and AFM suggest strongly that Ag segregated to the top of these samples at temperatures above 400 °C. In the absence of Ag, AFM evidence suggests that the Co growth mode appears to be Volmer–Weber island growth, but the morphology is much smoother with Ag present.