Recovery Process in Thin Films of Noble Metals Vacuum-Deposited on Low Temperature Substrate

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Abstract
Recovery of electrical resistivity of pure Au, Ag and Cu thin films deposited in vacuo on a mica sheet kept at liquid helium temperature was studied. Recovery process of Au films consists of several substages below 80°K, which are similar to those found in irradiated Au: The point defect recovery is strongly suggested. In the higher temperature region, both the point defect recovery and grain growth seem to be involved in the recovery process. The activation energies for recovery range from 0.013 eV (at 13°K) to 0.14 eV (at 55°K). The reaction is of the first order at around 25°K. Similar results have been obtained for Ag. In contrast to Au films, Ag and Cu films show remarkable reverse annealing between 20°K and 40°K, which presumably is closely connected with residual gas molecules such as oxygen. Some possible mechanisms of reverse annealing are also discussed.