Computer Simulation of Silicon Nanoscratch Test

By the molecular dynamics method, a computer simulation of a scratch test with a nanometer scale was performed. The specimen was composed of 1008 silicon atoms with a diamond single-crystal structure. The indentor was assumed to be a perfect rigid body, and the Morse potential was utilized as the interaction between the indentor and a silicon atom. Two types of potential, i.e., Stillinger-Weber and Tersoff potentials, were examined as the interaction between silicon atoms. The present simulation clarified that the standard deviation of the friction constant increased with decreasing scratch depth and became maximum when the indentor just began to scratch the specimen surface at critical load. The friction coefficient, indentation hardness and scratch hardness at critical load were estimated to be 1.2–1.6, 80–90 GPa and 8.5–9.4 GPa, respectively.