Low pressure annealing of gold nanostructures

•Ultra-thin Au films were prepared by sputtering on glass substrate.•Thermal annealing of Au coatings leads to dramatic increase of its surface roughness.•These changes are responsible for an increase of the film sheet resistance.•UV–Vis analysis proved the semiconducting characteristic of gold clusters.•Annealing under vacuum leads to the formation of more homogeneous gold layer.

Ultra-thin Au films sputtered on glass substrates were investigated. The samples were annealed in air and in an evacuated chamber. The dependence of the annealing process on ambient pressure during thermal treatment was studied. The thermally-induced changes in surface morphology were followed by atomic force microscopy. The changes have a great impact on dielectric, optical and physical properties of the prepared structures. UV–Vis absorption spectra were used to investigate optical parameters and showed the semiconducting characteristic of intrinsic Au clusters. It was found that reduced ambient pressure stabilizes the continuous structure of the thin gold film during the annealing process.