Bishara Hanna, Ghidelli Matteo, Dehm Gerhard
Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany.
ACS Appl Electron Mater. 2020 Jul 28;2(7):2049-2056. doi: 10.1021/acsaelm.0c00311. Epub 2020 Jul 1.
It is well-known that grain boundaries (GBs) increase the electrical resistivity of metals due to their enhanced electron scattering. The resistivity values of GBs are determined by their atomic structure; therefore, assessing the local resistivity of GBs is highly significant for understanding structure-property relationships. So far, the local electrical characterization of an individual GB has not received much attention, mainly due to the limited accuracy of the applied techniques, which were not sensitive enough to detect the subtle differences in electrical resistivity values of highly symmetric GBs. Here, we introduce a detailed methodology to probe or the local resistivity of individual GBs in Cu, a metallic model system we choose due to its low resistance. Both bulk Cu samples and thin films are investigated, and different approaches to obtain reliable and accurate resistivity measurements are described, involving the van der Pauw technique for macroscopic measurements as well as two different four-point-probe techniques for local measurements performed inside a scanning electron microscope. The contacts are realized with needles accurately positioned by piezodriven micromanipulators. Resistivity results obtained on coincidence site lattice GBs (incoherent Σ3 and asymmetric Σ5) are reported and discussed. In addition, the key experimental details as well as pitfalls in the measurement of individual GB resistivity are addressed.
众所周知，晶界（GBs）由于其增强的电子散射而增加金属的电阻率。晶界的电阻率值由其原子结构决定；因此，评估晶界的局部电阻率对于理解结构-性能关系具有重要意义。到目前为止，单个晶界的局部电学表征尚未受到太多关注，主要是由于所应用技术的精度有限，这些技术对检测高度对称晶界电阻率值的细微差异不够敏感。在这里，我们介绍一种详细的方法来探测或测量铜中单个晶界的局部电阻率，铜是我们因其低电阻而选择的金属模型系统。我们研究了块状铜样品和薄膜，并描述了获得可靠且准确的电阻率测量值的不同方法，包括用于宏观测量的范德堡技术以及用于在扫描电子显微镜内进行局部测量的两种不同的四点探针技术。通过压电驱动微操纵器精确定位的针实现接触。报告并讨论了在重合位置点阵晶界（非相干Σ3和不对称Σ5）上获得的电阻率结果。此外，还讨论了测量单个晶界电阻率时的关键实验细节以及陷阱。
