Silicon is widely used within energy, electro-mechanical, environmental devices by nanostructural control. As silicon parts constitute structural components whose size is ever decreasing, it is critical to understand the mechanical properties of single crystal silicon from precise measurements of load and displacement using microscopic sample in sub-micron and macroscopic scales. Here, the mechanical properties of single crystal silicon were precisely evaluated by bending tests at room temperature using microcantilever beam specimens having a several micron size. The microcantilever beam specimens were prepared using a focused ion beam technique, followed by loading the tip of the specimens. The smaller specimens deformed nonlinearly and then fractured. The unloaded specimen after nonlinear deformation showed permanent strain and many dislocations close to the region where high tensile stress was applied. This means that the nonlinear stress–strain relationship in the very high bending stress is determined by plastic deformation controlled by dislocation despite occurring at room temperature. The bending strength increased with a decrease in specimen size, and the smallest specimens had close to ideal strength. The size of the region where the dislocations accumulated in high density corresponded to the flaw size estimated from the fracture mechanics. This means that the bending strength of the microcantilever beam specimens of silicon is dominated by newly generated defects resulting from dislocations; in other words, the size effect of bending strength of silicon at the micrometer scale is controlled by the accumulation of newly formed dislocations because the dense dislocation region should be lower in a smaller-sized specimen.

中文翻译：

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室温下弯曲应力作用下单晶硅中位错控制的微观力学现象

硅通过纳米结构控制广泛用于能源、机电、环境设备。由于硅零件构成尺寸不断减小的结构部件，因此使用亚微米和宏观尺度的微观样品通过精确测量载荷和位移来了解单晶硅的机械性能至关重要。在这里，使用具有几微米尺寸的微悬臂梁试样在室温下通过弯曲试验精确评估了单晶硅的机械性能。使用聚焦离子束技术制备微悬臂梁试样，然后加载试样的尖端。较小的试样非线性变形，然后断裂。非线性变形后的卸载试样在施加高拉应力的区域附近显示出永久应变和许多位错。这意味着在非常高的弯曲应力中的非线性应力-应变关系是由位错控制的塑性变形决定的，尽管发生在室温下。弯曲强度随着试样尺寸的减小而增加，最小的试样具有接近理想的强度。位错高密度聚集区域的大小对应于从断裂力学估计的缺陷大小。这意味着硅微悬臂梁试样的弯曲强度主要由位错引起的新产生的缺陷决定；换句话说，