Nanoindentation of Silica Nanoparticles Attached to a Silicon Substrate

The nanomechanical properties of individual silica nanoparticles attached to a single crystal silicon (100) substrate were investigated using nanoindentation technique. The sample used in this study was fabricated by spin coating colloidal silica nanoparticle solution on the silicon substrate and then annealing the sample in a nitrogen environment. Environmental scanning electron microscopy (ESEM), scanning probe microscopy (SPM), and nanoindentation techniques were used to characterize the morphology and mechanical properties of the silica nanoparticles. The elastic modulus and hardness of the silica nanoparticles were found to be 68.9 ± 9.6 GPa and 2.8 ± 0.4 GPa, respectively. Several interesting phenomena were observed at the nanometer scale, including strain hardening, reverse plastic deformation, both ductile and brittle behaviors of the silica nanoparticles, and the increasing deformation resistance of the silica nanoparticles when subjected to repeated indentations.