Anisotropy in Nucleation and Growth of Two-Dimensional Islands during Homoepitaxy on "Hex" Reconstructed Au(100)

Abstract

We present results of a comprehensive scanning tunneling microscopy study of the nucleation and growth of Au islands on Au(100). It is shown that the reconstruction of the substrate produces strong anisotropic effects. Rate equation analysis of the experimental flux and temperature dependence of the island density suggests: (i) a critical size of $i=3\mathrm{}$ for $T=315-380\mathrm{}$ K, but $i>\mathrm{}3\mathrm{}$ above 400 K; and (ii) strongly anisotropic diffusion, preferentially parallel to the reconstruction rows (activation energy ∼0.2 eV). We comment on energetic and kinetic aspects of the observed island shape anisotropy.