Pattern Formation During Nanowear of Gold Films

Abstract

The effects of water on the wear resistance of 3 μm thick sputtered gold film on silicon substrate using contact AFM and a scanning nanoindenter were investigated. In performing wear tests on gold samples in the presence of water, a significant increase in depth of the wear area was observed compared to the same tests performed in the ambient atmosphere (∼55% humidity). These results were obtained using Hysitron Triboindenter on areas of 10×10 μm² and an Atomic Force Microscope on areas of 1×1 μm². Nanowear tests were preformed using silicon nitride cantilevers on the AFM and diamond Berkovich or blunt conical tips on the Hysitron. Normal loads used were 2000 μN and 10 μN, respectively. Tests performed in the ambient atmosphere resulted in a slightly reduced surface roughness, while a much higher wear rate was observed in the wear tests performed in water. Additionally, gold surface ripples formed under certain scanning conditions, in water for the Hysitron Triboindenter and in ambient atmosphere for the AFM. Nanoscale stick slip is being investigated as a possible explanation to the rippling phenomenon, and single scan line tests provide valuable information about the mechanisms and progression of the nanoscale wear.