Yielding and twinning in bulk and nanocrystalline semiconductors were considered based upon the activation of perfect or partial dislocation loops. Assuming that the yield stress of the crystal was proportional to the critical stress necessary for the activation of a perfect Frank-Read source, it was shown that for a range of crystal orientations with respect to the applied shear stress, the Hall-Petch relationship for a silicon polycrystal fails when the average grain diameter was of the order of 3 nm or less. It was further shown that, assuming the double-cross-slip mechanism of twin formation in silicon, twinning was easier than slip for a range of crystal orientations in nanocrystals.

Deformation Slip and Twinning in Bulk and Nanocrystalline Semiconductors. Z.A.Maryam, P.Pirouz, K.P.D.Lagerlöf: Journal of Physics - Conference Series, 2011, 281[1], 012018