Nucleation and growth of silver films deposited on mica substrates in ultra-high vacuum

Abstract

The nucleation and growth of silver films deposited in ultra-high vacuum over a wide range of substrate temperatures and deposition rates were studied using electron microscopy. As found previously, epitaxy occurred only if the mica was cleaved in vacuum and the temperature was in the region of 0°C or 300° C. The nuclei were nearly randomly oriented and their structure and concentration (6−7 × 10 11 cm −2) were virtually independent of the deposition conditions. Thus epitaxy was independent of nucleation and was determined only during the growth stages. During growth at ~ 300°C, coalescence was liquid-like throughout and misorientations between coalescing particles were removed continuously. At ~ 0°C, however, liquid-like coalescence ceased when particles exceeded ~ 300 Å in diameter and polycrystalline networks were formed which suddenly recrystallized into epitaxed sheets provided the rate of deposition was > 50 Å/min. These different modes of growth produced films with different defect distributions.