Reaction pathway analysis for dislocation nucleation from a sharp corner in silicon: Glide set versus shuffle set

Abstract

Using reaction pathway sampling, we have investigated the shear stress dependences of the activation energies of shuffle-set and glide-set dislocation nucleation from a sharp corner in silicon. The gradient of the glide-set dislocation curve is lower than that of the shuffle-set dislocation, and the athermal stress of glide-set dislocation is largely higher than that of shuffle-set dislocation. As a result, the two curves have a cross point, which means that shuffle-set dislocation is likely nucleated at high stress and low temperature and glide-set dislocation is likely nucleated at low stress and high temperature. Our result clearly explains the mechanism of recent molecular dynamics on these two types of dislocation nucleation at different temperatures and stress regimes. With increased compressive stress on the slip plane, the activation energy of the shuffle-set dislocation nucleation is greatly decreased, while that of glide-set dislocation nucleation is slightly increased. That would explain why shuffle-set dislocations were found under compressive stress fields.

Strength of silicon nanolayers under tensile loading

“…Godet et al confirmed using molecular dynamics (MD) simulations that each of these two dislocation sets can be activated in Si slabs from surfaces under tension at particular conditions [14]. At high temperatures and low tensile stress nucleation of dislocations in a glide set was observed, while at low temperatures and high tensile stress shuffle dislocation nucleation was reported [15]. In a different study Godet et al examined mechanism of mechanical failure of (001) surface oriented Si nanolayer on tensile direction [8].…”

Irreversible Deformation of Micron-Thick Single-Crystal Silicon in the Temperature Range of 350–500 °C

“…Molecular dynamics simulation becomes capable of analyzing the activation energies of dislocation nucleation under different conditions. (11) We expect that molecular dynamics could explain the decrease in BDT temperature under a severely strained Si crystal of micron thickness in the near future. …”

Review Article: Case studies in future trends of computational and experimental nanomechanics

“…Our view is that it is necessary to assess how experimental variables affect the above key variables in order to formulate a DBT model that does not depend on empirical constants. This requires understanding of how confining pressure, 205 radiation enhanced dislocation glide (REDG), 206 impurities, 207 state of stress, 208 and length scale 209 affect dislocation nucleation and mobility. The REDG effect 204 is important since most studies of length scale effects at submicron sizes are accomplished in either SEM or TEM.…”