Evaluation of Mechanical Properties for Nanometric Silicon Wire Used for Single Electron

本研究的重点是揭示样品尺寸和温度对用于单电子器件的纳米单晶硅(SCS)线材力学性能的影响。用原子力显微镜(AFM)对纳米SCS丝的弯曲性能进行了表征。采用原子力显微镜场增强阳极氧化和各向异性湿法腐蚀的方法，在硅膜片上制备了宽200~800 nm、厚255 nm的固定SCS丝。在高真空下，在295~573K的温度范围内对SCS丝进行了原子力显微镜弯曲试验。纳米SCS丝在室温下发生脆性断裂，但在373K以上发生塑性变形。在295K到573K的温度范围内，纳米SCS丝在(111)晶面上的杨氏模数平均为170GPa159 GP…。多a，但没有样本大小效应。然而，样品尺寸对断裂强度的影响很大，200 nm线材的断裂强度在17.8~15.9 GPA之间，是800 nm线材的1.5倍。在373K时，纳米SCS线材的塑性流动出现在力-位移曲线上，这是由于作用在线材上的高剪应力造成的。用原子力显微镜和扫描电子显微镜观察到了导致塑性流动的由刃位错组成的滑移线。纳米线的滑移线密度是微米级的100倍，这意味着试件的尺寸对塑性变形行为有很大的影响。新提出的刃位错模型能够合理地解释试件尺寸对高温塑性变形行为的影响是由试件尺寸与激活吉布斯自由能之间的关系决定的。最后，所研制的拉伸试验机上的静电致动器在纳米级拉伸试验中表现出了良好的性能。较少

This research focuses on revealing specimen size and temperature effects on mechanical properties of nanometric single crystal silicon (SCS) wires used for single electron devices. Mechanical properties of the nanometric SCS wires were characterized by bending tests with an atomic force microscope (AFM). The fixed-fixed SCS wires with widths from 200 nm to 800 nm and a thickness of 255 nm were fabricated on a silicon diaphragm by means of field-enhanced anodization with AFM and anisotropic wet etching. The AFM bending tests of the SCS wires were carried out at temperatures ranging from 295 K to 573 K in high vacuum. The tensile tesiting device including an electrostatic actuator and nanometric SCS wire was also designed.The nanometric SCS wires fractured in a brittle manner at room temperature, whereas they deformed plastically above 373 K. Young's modulus of the wires in the <110> direction on the (111) surface at temperature ranging from 295 K to 573 K averaged from 170 GPa to 159 GP … More a, respectively, but had no specimen size effect. However, the specimen size produced a large effect on the fracture strength since the fracture strength of the 200 nm-wide wires ranged from 17.8 GPa to 15.9 GPa, which were 1.5 times larger than that of the 800 nm-wide wires.Plastic flow of the nanometric SCS wires appeared in force-displacement curves at 373 K, which was caused by high shear stress acting on the wires. Slip lines comprised of edge dislocations responsible for the plastic flow was observed by AFM and SEM techniques. The slip line density of the nanometric wires was 100 times larger than that of the micrometer scale specimen, which meant the specimen size had a large influence on the plastic deformation behavior. The edge dislocation model newly proposed in this research was able to rationalize that the specimen size effect on the plastic deformation behavior at elevated temperature was determined by the correlation between the specimen size and the activation Gibbs free energy.Finally, the electrostatic actuator on the tensile testing device, developed here, gave a useful performance in the nanoscale tensile testing. Less