Effects of nanoindentation depth and annealing temperature on microstructural evolution of Au/Cr/Si thin films

Nanoindentation tests are performed on as-deposited Au/Cr/Si thin films to a depth of 1000 nm, respectively. The indentations in as-deposited and annealed specimens are examined using transmission electron microscopy (TEM). In the case of the as-deposited specimens, a pop-out feature is observed in the unloading curves and the indentation pressure induces a chain-like island structure and a distorted crystalline structure within the indentation zone. However, in the specimens annealed at temperatures of 250 degrees C and 350 degrees C, respectively, the microstructure of the indentation zone changes from a distorted crystalline structure to an amorphous phase. At an annealing temperature of 450 degrees C, the microstructure contains both amorphous phase and crystalline eutectic phase. The formation of eutectic phase is the result of a higher annealing temperature and a greater indentation deformation.