In situ investigation of growth of gold on crystalline TiO₂ and amorphous Al₂O₃ substrates

Abstract

The growth of thin gold films on highly crystalline TiO₂ and amorphous Al₂O₃ substrates and its dependence on substrate temperature was investigated under UHV-conditions by in situ internal stress measurements. Deposition of gold on amorphous Al₂O₃ at substrate temperatures between 27°C and 300°C shows a stress vs. thickness curve which indicates island growth at first and the formation of a polycrystalline film at higher thickness. A comparable stress vs. thickness curve is found for the growth of gold on the highly crystalline TiO₂ substrate at substrate temperatures below 200°C, again indicating island growth. At higher temperatures, however, a new tensile stress feature at low gold coverage is interpreted to indicate the formation of a strained interface layer. This strain in the gold film is eliminated after deposition of a few monolayers most likely through incorporation of dislocations and defects. The growth stress at higher film thickness is indicative of island film growth.