Mechanisms of plasticity in near-theoretical strength sub-100 nm Si nanocubes

Silicon is one of the most technologically important materials, used extensively in electronics, solar cells, micro-electro-mechanical systems (MEMS) based devices and more. Yet its mechanical properties are not well understood at the nanoscale where it is often utilized. Experimental measurements under a variety of loading conditions are needed, and compression experiments are particularly lacking. Here, the elastic-plastic response of 20-65 nm cubic Si nanocubes under uniaxial compression is investigated. The purely elastic limit of these nanocubes is observed to be up to 0.07 true strain at 7 GPa true stress with an upper yield point of 0.20 true strain and 11 GPa true stress. Investigation of the nature of dislocations generated during deformation of these nanocubes using post-mortem analysis in the TEM provides evidence that leading partial dislocations are the dominant source of plasticity at this scale.