Elastic Properties and Buckling of Silicon Nanowires

Silicon is the most important material for the electronics industry. Its unique electronic, optoelectronic, thermal, and mechanical properties have made Si an ideal choice for integrated circuits, memory devices, solar cells, and microelectromechanical systems (MEMS). Considering onedimensional (1D) nanomaterials, carbon nanotubes, silicon nanowires, and ZnO nanowires/nanobelts are the three primary structures of choice, because of their largely improved, different, and/or unique properties at the nanometer scale. As the sizes of MEMS approach nanoelectromechanical systems (NEMS), exploration of the changes of mechanical properties on the nanometer scale is vitally important. Silicon nanowires (NWs) are the key building blocks of future electronics. Several approaches have been developed to study the mechanical behavior of Si nanowires. The existing literature reports progress in observing the phenomenon of plasticity and in measuring the elastic modulus of single NWs or NW arrays. In this Communication, we report using a manipulation probe and an atomic force microscope (AFM) tip in scanning electron microscopy (SEM) to investigate the mechanical behavior of a single SiNW under buckling and bending conditions. Some of the mechanical properties of SiNWs have been quantified. Our study has demonstrated the tough and robust behavior of SiNWs. The SiNWs used for our experiments were fabricated by chemical vapor deposition by the vapor–liquid–solid (VLS) growth process. Figure 1 shows a transmission electron microscopy (TEM) image of an as-grown SiNW, revealing its core/shell structure. The diameters of the NWs are 40–90 nm. The thickness of the outer native oxide layer is about 5 nm. The inset shows a diffraction pattern, revealing the single-crystalline structure of the NWs.