Yagi Mamiko, Shirakashi Jun-Ichi
Division of Electrical and Electronic Engineering, Department of Engineering for Future Innovation, Ichinoseki College (Ichinoseki KOSEN), Ichinoseki, Iwate 021-8511, Japan.
Department of Electrical and Electronic Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Materials (Basel). 2019 Jan 19;12(2):310. doi: 10.3390/ma12020310.
The nanoscale heat dissipation (Joule heating) and mass transport during electromigration (EM) have attracted considerable attention in recent years. Here, the EM-driven movement of voids in gold (Au) nanowires of different shapes (width range: 50⁻300 nm) was directly observed by performing atomic force microscopy. Using the data, we determined the average mass transport rate to be 10⁵ to 10⁶ atoms/s. We investigated the heat dissipation in L-shaped, straight-shaped, and bowtie-shaped nanowires. The maximum Joule heating power of the straight-shaped nanowires was three times that of the bowtie-shaped nanowires, indicating that EM in the latter can be triggered by lower power. Based on the power dissipated by the nanowires, the local temperature during EM was estimated. Both the local temperature and junction voltage of the bowtie-shaped nanowires increased with the decrease in the Joule heating power and current, while the current density remained in the order of 10⁸ A/cm². The straight-shaped nanowires exhibited the same tendency. The local temperature at each feedback point could be simply estimated using the diffusive heat transport relationship. These results suggest that the EM-driven mass transport can be controlled at temperatures much lower than the melting point of Au.
近年来，电迁移（EM）过程中的纳米级热耗散（焦耳热）和质量输运引起了广泛关注。在此，通过原子力显微镜直接观察了不同形状（宽度范围：50⁻300 nm）的金（Au）纳米线中电迁移驱动的空洞运动。利用这些数据，我们确定平均质量输运速率为10⁵至10⁶个原子/秒。我们研究了L形、直形和领结形纳米线中的热耗散。直形纳米线的最大焦耳热功率是领结形纳米线的三倍，这表明后者中的电迁移可以由较低功率触发。基于纳米线耗散的功率，估算了电迁移过程中的局部温度。领结形纳米线的局部温度和结电压都随着焦耳热功率和电流的降低而升高，而电流密度保持在10⁸ A/cm²的量级。直形纳米线也表现出相同的趋势。每个反馈点的局部温度可以使用扩散热输运关系简单估算。这些结果表明，在远低于金熔点的温度下，可以控制电迁移驱动的质量输运。
