An atomic scale characterization of coupled grain boundary motion in silicon bicrystals

Abstract

The mechanical response of symmetric tilt grain boundaries (GBs) in silicon bicrystals under shear loading are characterized using molecular dynamics simulations. It is seen that under shear, high-angle GBs namely Σ5 and Σ13 having a rotation axis [0 0 1] demonstrate coupled GB motion, such that the displacement of grains parallel to the GB interface is accompanied by normal GB motion. An atomic-scale characterization revealed that concerted rotations of silicon tetrahedra within the GB are the primary mechanisms leading to the coupled GB motion. Interestingly, so far, this phenomenon has only been examined in detail for metallic systems. A distinguishing feature of the coupled GB motion observed for the silicon symmetric tilt bicrystals as compared to metallic bicrystals is the fact that in the absence of shear, spontaneous coupled motion is not observed at high temperatures.

Keywords:

• grain boundary motion
• grain boundary coupling
• silicon
• bicrystals

Acknowledgements

The author S.B. gratefully acknowledges the Thomas G. Chapman Fellowship awarded by the College of Engineering at the University of Arizona.

Disclosure statement

No potential conflict of interest was reported by the authors.