Effect of residual stresses on the stability of bct-5 silicon

• The bct-5 Si has a great future in the fabrication of opto-electronic devices.
• bct-5 Si can be generated by scratching the {1 0 0} surface along [1 1 0] direction.
• Hydrostatic stress plays a key role in the initiation and development of bct-5 Si.
• Residual octahedral shear stress of 6–8 GPa is required to have stable bct-5 Si.

This paper investigates the effect of residual stresses on the stability of the bct-5 silicon phase induced by nano-scratching using a diamond cutting tip. The molecular dynamics method was used to simulate the scratching process and stress analysis. The Tersoff potential was employed to describe the interaction of silicon atoms and the Morse potential was used for the interaction of silicon and carbon atoms of the cutting tip. It was found that scratching the {1 0 0} surface of silicon along the 〈1 1 0〉 direction can initiate the phase transformation of silicon from its diamond structure to bct-5 in the subsurface. The study concluded that the hydrostatic stress component under the cutting tip plays an important role in the initiation and development of the bct-5 phase during nano-scratching, but a residual octahedral shear stress of 6–8 GPa is required to make the bct-5 silicon stable after the nano-scratching.