Nanowear of gold and silver against silicon

We studied the wear behavior of gold (Au) and silver (Ag) against a single crystal silicon (Si) within a highly localized area. The nanowear was generated at the tip of an atomic force microscope (AFM) and was chemically activated by Si during sliding. AFM tips were coated with gold or silver thin films. During experiments, the coated AFM tip slided against the surface of a Si wafer. It was found that both Au and Ag tips showed combined abrasive as well as adhesive wear. In addition to the wear scar on the AFM tip, Si was found on both (Au- and Ag-coated) probes after sliding. On the Si substrate, instead of a wear track, a well-defined line structure was generated. Energy comparison of the Au-Si and Ag-Si eutectic systems indicates that Au is more thermodynamically activated by Si than Ag. During sliding, mechanical energy promotes the interfacial reaction.