Grain boundary self-diffusion in evaporated Au films at low temperatures

Direct self-diffusion measurements in vapor-deposited polycrystalline Au films have been made using ¹⁹⁵Au radioactive tracer and an r.f. back-sputtering technique for serial sectioning. A temperature range of 117°–177°C was investigated. It has been demonstrated that self-diffusion in thin Au films at these low temperatures takes place by rapid transport of the tracer atoms along the grain boundaries. The grain boundary self-diffusion parameters are Q_b=1.0±0.1 eV and δD_b⁰ = 9 × 10^?10 cm³/sec, which compare well with those in bulk polycrystalline Au.