Atomistic mechanisms for the ordered growth of Co nanodots on Au(7 8 8): a comparison between VT-STM experiments and multi-scaled calculations

Abstract

Hetero-epitaxial growth on a strain-relief vicinal patterned substrate has revealed unprecedented 2D long range ordered growth of uniform cobalt nanostructures. The morphology of a sub-monolayer Co deposit on a Au(1 1 1) reconstructed vicinal surface is determined by using variable temperature scanning tunneling microscopy (VT-STM). A rectangular array of nanodots (3.8 nm × 7.2 nm) is found for a particularly large deposit temperature range lying from 65 to 300 K. This paper focuses on the early stage of growth at temperatures between 35 and 480 K. Atomistic mechanisms leading to the nanodots array are elucidated by comparing statistical analysis of VT-STM images with multi-scaled numerical calculations. Molecular dynamics allows the quantitative determination of the activation energies for the atomic motion, whereas the kinetic Monte Carlo method simulates the submonolayer Co growth over mesoscopic time scale and space scale.