Nucleation and growth of vacuum-deposited metal aggregates studied by electron microscopy

Data are presented on the kinetics of growth of metal aggregates formed in the initial stages of vacuum deposition on amorphous substrates. These data suggest a refinement of the model used to describe earlier results. The model involves active sites at which the metal aggregates nucleate and diffusion into the substrate of atoms incident at locations removed from these active sites. The essential feature of the model is the concept of a capture zone of constant width surrounding each active site or growing metal aggregate. Metal atoms incident on the capture zone can migrate to the associated cluster, and become incorporated therein. This modification produces a model which is analyzed to give growth curves with only one adjustable parameter: the width of the capture zone. Data for Ag, Au, Pd, and Pt on vacuum-deposited carbon are all fit with a capture-zone width of 6.5 Å.