Abstract
The early growth stages of sputtered (S) vs evaporated (E) Ag/mica and Ag/NaCl films have been studied by transmission electron microscopy and electron diffraction. The observed maximum density of the islands at thicknesses less than 20 Å is slightly higher for S films, although the order of magnitude is the same (∼1011/cm2) for both the S and E films. Electrostatic charges carried by the S atoms and the point defects caused by the penetration of the energetic S atoms could account for the observed higher S‐island density. As the film thickness increases, the S‐island density at 25°C decreases rapidly to reach a constant value before the film becomes continuous. The corresponding E‐island density decreases slowly. The higher mobility, as indicated by the rate of change of the island density, and the observed epitaxial growth of the S films at a temperature considerably lower than that obtained for E films, are attributed to the higher kinetic energy of the S atoms. The E‐island density decreases rapidly as the substrate temperature is increased. The decrease in S‐island density is, however, accompanied by an increase in the surface area of the islands and formation of bridges between the islands, thereby resulting in coalescence at a smaller nominal thickness than is observed in E films. These observations are explained on the basis of the effects of higher electrostatic charges and kinetic energy of the S atoms. The activation energies for the diffusion processes, calculated from the temperature dependence of the separation between the islands, are 0.1 and 0.15 eV for S and E films, respectively, at substrate temperature below 250°C. Above 250°C, the activation energies increase rapidly to 0.5 and 0.9 eV, respectively.

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