Nanoindentation based fracture studies of ITO coating

Nano-scale load (P) dependency of fracture toughness (K-1C) of indium tin oxide (ITO) coating on silicon (Si) substrate is evaluated by nanoindentation based direct and energy methods. A Berkovich triangular diamond nanoindenter is used with nine different P values e.g., 10, 15, 20, 30, 40, 50, 100, 150 and 200 mN. Extensive utilization of both optical microscopy (OM) and field emission scanning electron microscopy (FESEM) techniques reveal that up to P <= 40 mN only the sharp radial cracks form from three corners of the nanoindent. However, for P > 40 mN, multiple cracks occur over and above the radial cracks. Finally, at P: 150-200 mN coating gets chipped off from the substrate. The K-1C values of the ITO coating are calculated on the basis of both the conventional radial crack length measurement based method and the strain energy release based method. The K-1C values are strongly sensitive to variations in P. Further, the strain energy method results in higher magnitudes of the K-1C values.

Automated summary

The study evaluates the nano-scale load dependency of fracture toughness of indium tin oxide coating on silicon substrate using nanoindentation methods. It is observed that at loads above 40 mN, multiple cracks form in addition to the radial cracks, eventually leading to coating chipping off at 150-200 mN. The values of fracture toughness are sensitive to load variations and the strain energy release method results in higher values.