The mechanical properties characterization of silicon nanowires is generally performed by tensile nanomechanical loading tests with in situ strain quantification. While the strain is characterized by electron beam (e-beam) microscopy techniques, the understanding of the sample-electron interaction is essential to guarantee artifact-free measurements. In this work, we investigated suspended strained silicon nanowires under electron beam exposure in a scanning electron microscope (SEM). The fabricated nanowires had their initial stress profile characterized by Raman spectroscopy and finite element method simulations. Then, the sample was exposed to an e-beam where we observed a gradual electrical charging of the sample, verified by the image drift, and down deflection of the suspended nanowire caused by electrostatic forces. These additional stresses induced the mechanical fracture of the nanowires in the corner region due to accumulated stress. These results ascribe electrostatic mechanical loading concerns that may generate undesirable additional stresses in nanomechanical tests performed in SEM, demonstrating the importance of proper sample preparation to avoid electrostatic charging effects. Here, we propose a simple and effective method for imposing the structures under an impinging electron beam at an equipotential, which mitigates the charging effects acting on the nanowire.

中文翻译：

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悬浮应变硅纳米线的原位电子束诱导机械载荷和断裂

硅纳米线的机械性能表征通常通过原位拉伸纳米机械加载试验进行应变量化。虽然应变的特征在于电子束 (e-beam) 显微镜技术，但了解样品-电子相互作用对于保证无伪影测量至关重要。在这项工作中，我们研究了在扫描电子显微镜 (SEM) 中电子束曝光下的悬浮应变硅纳米线。制造的纳米线具有通过拉曼光谱和有限元法模拟表征的初始应力分布。然后，将样品暴露在电子束下，我们观察到样品逐渐充电，通过图像漂移和静电力引起的悬浮纳米线的向下偏转来验证。由于累积应力，这些额外的应力导致拐角区域的纳米线发生机械断裂。这些结果归因于静电机械载荷问题，可能会在 SEM 中进行的纳米力学测试中产生不希望的额外应力，证明了正确样品制备以避免静电充电效应的重要性。在这里，我们提出了一种简单有效的方法，用于在等电位撞击电子束下施加结构，从而减轻作用在纳米线上的充电效应。