Amorphization of gold film on silicon single crystal by hardness indentation at room temperature

The formation of an amorphous gold-silicon alloy by indentation is reported. A polycrystalline gold film formed via vapour deposition on a silicon (111) substrate was indented using a Berkovich indenter with a load of 0.05 N. The indentation area was observed by transmission electron microscopy after thinning the silicon substrate from the back side (unindented surface). A set of halo rings, identified as an amorphous gold-silicon alloy was observed. A gold film on a SiO2 substrate was also used to investigate the effect of the substrate, and no amorphization was observed. The amorphization mechanism is discussed based on thermodynamics.