Department of Physics, ETH Zurich , Otto Stern Weg 1, 8093 Zurich, Switzerland.
Nano Lett. 2017 Apr 12;17(4):2367-2373. doi: 10.1021/acs.nanolett.6b05304. Epub 2017 Mar 24.
Charge transport in nanostructures and thin films is fundamental to many phenomena and processes in science and technology, ranging from quantum effects and electronic correlations in mesoscopic physics, to integrated charge- or spin-based electronic circuits, to photoactive layers in energy research. Direct visualization of the charge flow in such structures is challenging due to their nanometer size and the itinerant nature of currents. In this work, we demonstrate noninvasive magnetic imaging of current density in two-dimensional conductor networks including metallic nanowires and carbon nanotubes. Our sensor is the electronic spin of a diamond nitrogen-vacancy center attached to a scanning tip and operated under ambient conditions. Using a differential measurement technique, we detect DC currents down to a few μA with a current density noise floor of ∼2 × 10 A/cm. Reconstructed images have a spatial resolution of typically 50 nm, with a best-effort value of 22 nm. Current density imaging offers a new route for studying electronic transport and conductance variations in two-dimensional materials and devices, with many exciting applications in condensed matter physics and materials science.
纳米结构和薄膜中的电荷输运是科学和技术中许多现象和过程的基础，从介观物理中的量子效应和电子相关，到基于电荷或自旋的集成电子电路，再到能源研究中的光活性层。由于这些结构的纳米尺寸和电流的巡游性质，直接可视化它们中的电荷流动具有挑战性。在这项工作中，我们展示了对二维导体网络（包括金属纳米线和碳纳米管）中电流密度的非侵入式磁成像。我们的传感器是附着在扫描尖端上的金刚石氮空位中心的电子自旋，在环境条件下运行。使用差分测量技术，我们可以检测到低至几微安的直流电流，电流密度噪声基底约为 2×10^-10 A/cm。重建的图像具有典型的 50nm 空间分辨率，最佳分辨率为 22nm。电流密度成像为研究二维材料和器件中的电子输运和电导变化提供了一条新途径，在凝聚态物理和材料科学中有许多令人兴奋的应用。
