The temperature-dependent growth of Fe submonolayer film on Au(001) studied by barrier height imaging using scanning tunneling microscopy

The growth of Fe submonolayer films on Au(001) at various substrate temperatures (300–500 K) was investigated by scanning tunneling microscopy (STM). STM topographic and barrier height images show that the growth mode and morphology of the films markedly depend on growth temperature. Fe islands with a monolayer height nucleate and grow on flat terraces of Au(001) at 300 K. However, Fe islands with double-layer height and small pinholes were observed on terraces at 353 and 393 K, and step edges were decorated by Fe dendrites. A clear element-specific contrast between Fe islands and Au substrate was observed below 400 K. At elevated growth temperature, above 400 K, a segregated Au layer was observed. The mechanism of the surface segregation of Au is also discussed in terms of the surface diffusion through the pinholes.