Young's modulus size effect of SCS nanobeam by tensile testing in electron microscopy

In-situ tensile testing in EM (electron microscopy) is a useful tool for studying mechanical properties of nano-structures because it can provide quantitative information on sample deformation at atomic scale. In this work, MEMS tensile-testing chips with differently thick <110>-oriented SCS nanobeams were designed, fabricated and utilized in SEM and/or TEM to manipulate SCS nanobeam and measure its strain and stress in nano scale. We obtained Young's modulus of SCS nanobeams with thicknesses from 30 nm to 100 nm, and found that E decreased monotonously with the beams decreasing thickness. A simple modal was constructed to qualitatively illustrate this size dependence by taking surface effect into account and it shows that surface layers have different effects on E in tensile testing from that in resonant testing.