Numerical and experimental investigation on ductile deformation and subsurface defects of monocrystalline silicon during nano-scratching

Abstract

Nano-scratching is an indispensable approach for investigating the ductile deformation and subsurface defects produced during nano-machining of hard, brittle material. In this study, three-dimensional molecular dynamic (MD) simulations of nano-indentation and nano-scratching were conducted on monocrystalline silicon using a diamond indenter with various tip radii. Under the same scratching speed, crystal orientation, and depth, comparative analyses were performed among the results of nano-scratching with indenter tip radii of 2, 4, and 6 nm. The interactions between C and Si atoms and the interactions among Si atoms are described in terms of the Tersoff empirical potential. The effects of the tip radius on the ductile deformation, scratching force, and subsurface defect thickness during the nano-scratching process were analysed in depth. Then, nano-scratching experiments using a self-developed device were conducted to verify the simulation results through a comparison. The Raman spectroscopy and electron backscattered diffraction techniques were used to detect the crystal structure evolution and subsurface defect thickness. The experimental results were observed to be in agreement with the MD simulation results.