Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region (SAR) 999077, China.; Centre for Advanced Structural Materials, City University of Hong Kong, Hong Kong SAR 999077, China.
IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, USA.
Sci Adv. 2016 Aug 17;2(8):e1501382. doi: 10.1126/sciadv.1501382. eCollection 2016 Aug.
Achieving high elasticity for silicon (Si) nanowires, one of the most important and versatile building blocks in nanoelectronics, would enable their application in flexible electronics and bio-nano interfaces. We show that vapor-liquid-solid-grown single-crystalline Si nanowires with diameters of ~100 nm can be repeatedly stretched above 10% elastic strain at room temperature, approaching the theoretical elastic limit of silicon (17 to 20%). A few samples even reached ~16% tensile strain, with estimated fracture stress up to ~20 GPa. The deformations were fully reversible and hysteresis-free under loading-unloading tests with varied strain rates, and the failures still occurred in brittle fracture, with no visible sign of plasticity. The ability to achieve this "deep ultra-strength" for Si nanowires can be attributed mainly to their pristine, defect-scarce, nanosized single-crystalline structure and atomically smooth surfaces. This result indicates that semiconductor nanowires could have ultra-large elasticity with tunable band structures for promising "elastic strain engineering" applications.
实现硅（Si）纳米线的高弹性，硅纳米线是纳米电子学中最重要和用途最广泛的构建模块之一，这将使它们能够应用于柔性电子和生物纳米界面。我们表明，直径约为 100nm 的气-液-固生长的单晶 Si 纳米线可以在室温下反复拉伸超过 10%的弹性应变，接近硅的理论弹性极限（17%至 20%）。少数样品甚至达到了约 16%的拉伸应变，估计断裂应力高达约 20GPa。在不同应变速率的加载-卸载测试中，这些变形是完全可逆且无滞后的，失效仍然发生在脆性断裂中，没有明显的塑性迹象。Si 纳米线能够实现这种“深度超高强度”，主要归因于其原始的、缺陷稀少的、纳米级的单晶结构和原子级光滑的表面。这一结果表明，半导体纳米线可以具有超弹性和可调带结构，有望实现“弹性应变工程”应用。
