Size-dependent brittle-to-ductile transition in GaAs nano-rods

Abstract

a b s t r a c tGaAs is brittle at room temperature at the macro-scale; however, ductility emerges when its characteristic dimension reduces to the nano-scale. Using molecular dynamics simulations, we reveal that there is a brittle-to-ductile transition in GaAs nano-rods due to the competition between generation of cracks and initiation of dislocations. Such a competition is sensitive to aspect ratios of nano-rods. These results well explain experimentally observed ductility of GaAs nano-rods and have important implications for the design of semiconductor materials with tailored mechanical properties.

Simulation Study on the Defect Generation, Accumulation Mechanism and Mechanical Response of GaAs Nanowires under Heavy-Ion Irradiation

“…Secondly, as shown in the partial cross-sectional structure in Figure 9c, nanostructures that are under high ion-dose appear as 1/6<112> dislocation types, whose motion ensures plastic deformation. It is also demonstrated in the study of Wang et al [31] In terms of Young's modulus, Figure 9d shows that the mechanical parameters usually decrease with increasing dose, reaching saturation at doses greater than 4 × 10 14 ions/cm 2 at 5 keV energy. Point defects and small clusters induce changes in the mechanical properties of GaAs NWs at low ion doses, while a crystalline to amorphous (c-a) transition occurs at high doses, saturating the mechanical properties.…”

“…For the simulation part of ion implantation, we have adopted the hybrid potential by Albe et al [36] and Gao et al [10] In terms of the tensile deformation simulations, we use the Vashishta potential function which is very close to the experimental value in describing the elastic constants of the GaAs crystal [37]. This potential function has been used several times to simulate the stretching and compression of GaAs NWs, showing a series of mechanical characteristics such as size effect, brittle to ductile transition, and self-healing phenomena, all of which have been demonstrated in the experiment [30,31]. The parameters related to the Vashishta potential are taken from Ref.…”

“…Furthermore, a complete synthesis model of GaAs NW including 29376 atoms with the [111] axis and six side facets [29] is shown in Figure 1b, where the X, Y and Z axes are oriented along , [1][2][3][4][5][6][7][8][9][10] and [111] directions, respectively. The longitudinal length of NWs is about 33 nm and the cross-sectional diameter is about 5.5 nm to maintain the aspect ratio of 6:1 [30,31].…”

Piezoelectric-conductor iterative method for analysis of cracks in piezoelectric semiconductors via the finite element method

“…Wang et al [15] revealed that there is a brittle-to-ductile transition in GaAs nano-rods because of the competition between the generation of cracks and initiation of dislocations.…”