Nanoscratch behaviors of SiO2/Si bilayer materials: A molecular dynamics study

J Chen and YY Dai and L Fang and HQ Chen and Z Wang and FM Qin, MATERIALS TODAY COMMUNICATIONS, 48, 113523 (2025).

DOI: 10.1016/j.mtcomm.2025.113523

This work explores the friction and wear behaviors of monocrystalline silicon coated with an amorphous SiO2 film by nanoscratching test against an amorphous SiO2 tip using molecular dynamics simulation. The results indicate that the friction force increases with increasing normal force and growing thickness of SiO2 film for bilayer composites with thinner films under the same normal force. The friction force curves of the bilayer samples are serrated owing to inhomogeneous plastic deformation and material removal of amorphous SiO2 films, while the curve for monocrystalline silicon is relatively smooth. Material removal occurs to the tested bilayer samples during scratching when the Si-O bonds generate between the samples and the deformed (densification, sheared) tip. The variations of removed atoms and deformation analysis of the scratched SiO2 film verify that the material removal dominates the densification at the initial stage of scratching, then densification surpasses material removal. Higher normal force significantly promotes a higher material removal rate (MRR) and lower surface quality. The MRR grows slightly with the thickness of the film under the normal force, except for 0.2 nm sample. The removal mechanism is indentation-adhesion between bilayer samples and SiO2 tip.

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