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

•The uniaxial compressive behavior of GaAs nano-rods was investigated by using molecular dynamics.•Buckling beyond the elastic limit induces a competition between generation of cracks and initiation of dislocations.•Dislocation activities dominate plastic deformation and whilst the preference to cracks yields brittle fracture.•The brittle-to-ductile transition is significantly size-dependent. GaAs 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.