Dependence of Peierls stress on lattice strains in silicon

Several non-Schmid effects of plasticity in Si are discussed in this article. The contribution of shear strain applied in the direction of the Burgers vector and normal to it in the glide plane, and of strain applied normal to the glide plane to defining the Peierls stress are analyzed. The analysis is performed using a combination of atomistic simulations and the Peierls-Nabarro model based on generalized stacking faults. It is shown that a shear strain acting in the direction of the Burgers vector decreases the Peierls stress and the effect is due to the reduction of the shear modulus. Bonding across the glide plane has the most important contribution to the Peierls stress, but the elastic non-linearity of the surrounding material contributes to reducing the instability threshold. A shear strain acting perpendicular to the Burgers vector has no effect on the Peierls stress. A compressive strain normal to the glide plane reduces the Peierls stress for shuffle dislocations and has a weak increasing effect on the critical stress of glide-set dislocations.