Nanomechanical properties of a Ni nanodot-patterned surface

Nanomechanical properties of a Ni nanodot-patterned surface (NDPS) on a Si substrate were investigated using nanoindentation. The Ni NDPS was fabricated by thermal evaporation of Ni through a porous anodized aluminum oxide template onto a Si substrate. Plan-view transmission electron microscopy and nanobeam diffraction were used to characterize the Ni nanodot crystal structure. Scanning electron microscopy and atomic force microscopy were used to characterize the morphology and deformation of the Ni nanodots before and after nanoindentation. The elastic modulus and hardness of the Ni nanodots were found to be 159 ± 22 and 7.7 ± 1.0 GPa, respectively. The critical shear stress for initiating plastic deformation in the Ni nanodot was estimated to be 8.3 ± 1.0 GPa, which is close to the theoretical shear strength of 7.6 GPa in dislocation-free single crystal Ni.