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 30nm to 100nm, 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.