Crack propagation of Si nanofilm accompanied by initial stage of wet oxidation

Y Sun and Z Zhai and BJ Qiao and SH Tian and XF Chen, APPLIED SURFACE SCIENCE, 505, 144200 (2020).

DOI: 10.1016/j.apsusc.2019.144200

Motivated by our recent research presenting the effect of dry oxidation on crack propagation of Si nanofilm, water environment was taken into account in this work to clarify how crack propagates accompanied by initial wet oxidation which is influential for nanoscale devices in aqueous environment. By Reactive force field molecular dynamics (ReaxFF MD) simulation, the fracture strength during crack propagation by simultaneous oxidation with water was calculated. The atomic configurations were tracked as well. It demonstrated that the initial wet oxidation improved fracture toughness and retarded crack propagation to some extent, although less obvious than that of dry oxidation. The initial stage oxidation of crack tip and the oxide structures have been analyzed, showing that hydrogen dissociated from water was attractive to bond with Si under tension. The number of absorbed oxygen into Si by water oxidant was lower than that with dry one at same temperature, accordingly forming less Si-O bonds which released the tension at crack tip to enhance the fracture strength in a minor way. The influence of initial wet oxidation on crack propagation investigated here could be helpful on deeply understanding the mechanical property of nanoscale devices under aqueous environment fabrication and application.

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