A Molecular Dynamics Study of Tilt Grain Boundary Resistance to Slip and Heat Transfer in Nanocrystalline Silicon


We present a molecular dynamics study of grain boundary (GB) resistance to dislocation-mediated slip transfer and phonon-mediated heat transfer in nanocrystalline silicon bicrystal. Three most stable (110) tilt GBs in silicon are investigated. Under mechanical loading, the nucleation and growth of hexagonal-shaped shuffle dislocation loops are reproduced. The resistances of different GBs to slip transfer are quantified through their constitutive responses. Results show that the Σ3 coherent twin boundary (CTB) in silicon exhibits significantly higher resistance to dislocation motion than the Σ9 GB in glide symmetry and the Σ19 GB in mirror symmetry. The distinct GB strengths are explained by the atomistic details of the dislocation-GB interaction. Under thermal loading, based on a thermostat-induced heat pulse model, the resistances of the GBs to transient heat conduction in ballistic-diffusive regime are characterized. In contrast to the trend found in the dislocation-GB interaction in bicrystal models with different GBs, the resistances of the same three GBs to heat transfer are strikingly different. The strongest dislocation barrier Σ3 CTB is almost transparent to heat conduction, while the dislocation-permeable Σ9 and Σ19 GBs exhibit larger resistance to heat transfer. In addition, simulation results suggest that the GB thermal resistance not only depends on the GB energy but also on the detailed atomic structure along the GBs.



Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Bicrystals; Crystal Atomic Structure; Grain Boundaries; Heat Conduction; Heat Transfer; Molecular Dynamics; Nanocrystalline Silicon; Nanocrystals; Silicon; Diffusive Regime; Dislocation Motion; Mechanical Loading; Nucleation and Growth; Shuffle Dislocations; Thermal Loadings; Tilt Grain Boundary; Transient Heat Conduction; Heat Resistance

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Article - Journal

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© 2014 American Institute of Physics Inc., All rights reserved.

Publication Date

01 Jan 2014