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Elastic properties of nanowires

: Röhlig, C.-C.; Niebelschütz, F.; Brueckner, P.; Tonisch, K.; Ambacher, O.; Cimalla, V.


Physica status solidi. B 247 (2010), No.10, pp.2557-2570
ISSN: 0031-8957
ISSN: 0370-1972
Conference "Nanowires and Nanotubes - From Controlled Synthesis to Functions" <2010, Freiburg>
Journal Article, Conference Paper
Fraunhofer IAF ()
elasticity; nanoelectromechanical system; nano lithography; nanowire; Young's modulus

The elastic properties of metallic and semiconducting nanowires were analyzed by different techniques employing static and dynamic loads. The reliability of the methods is verified by analyzing well defined microstructures and a good agreement for the values of the Young's modulus determined by the different methods was achieved. For the investigated materials systems (Au, W, Si, InN), basically no differences in the Young's moduli were observed between microstructures, bulk material, and nanowires with radii of 20-300 nm. Microstructure, morphological undulation, defects, and contaminations,however, can drastically change the apparent Young's moduli of nanowires. Examples are given, where an apparent increasing or decreasing of the Young's modulus with decreasing diameter is caused by such effects. The same effects have also influence on the fracture strength in nanowires. While perfect Au nanowires exhibit fracture strengths exceeding the bulk values up to two orders of magnitude, any anomaly causes earlier failure. In addition, failure mechanisms are observed to be dependent on themicrostructure. While single crystallineAu nanowires have shown a pure elastic deformation upon load, polycrystalline nanowires show a remarkable plastic deformation before breaking.