Size effects on the mechanical properties of VLS-grown Si Nanowires

Abstract

Nanowires are known to show different properties from their bulk counterparts. Generally, their defect-free structure and high surface-to-volume ratio are considered as a cause of this phenomenon and those factors make the properties, especially electrical and mechanical, of one-dimensional nano-structures better than those of bulks. In the present work, we systematically investigate the variation in the mechanical properties of nanowires with varying diameters by using two different nano-mechanical testing methods: bending test and nanoindentation. Examined materials were Si nanowires, grown by vapor-liquid-solid (VLS) methods, with a diameter from ~20 to 200 nm. Atomic force microscopy (AFM) and commercial nanoindentation equipment were used for the experiments. First, from load-displacement data, we estimated the values of elastic modulus and yield strength. Then, we analyzed the size effects on mechanical properties of the nanowires. * This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government, MEST (No. R01-2008-000-20778-0).