On the role of kinks and strain in heteroepitaxial growth: An STM study

Interlayer diffusion of Co over steps of vacancy islands on the Pt(111) sur face as studied by scanning tunneling microscopy is presented. It is demons trated that Co atoms descend Pt steps by an exchange diffusion process at t he step edge with the Pt atoms. Further, the exchange diffusion process is observed to occur at the corners (kinks) of the vacancy islands. The import ance of kinks concerning whether the growth mode of a heteropitaxial film i s two-dimensional or three-dimensional is demonstrated for the case of thin Co films on Pt(111). We argue that the strain in the Co film is to a large extent responsible for the kink formation.