通过近场光电流纳米术揭示一维缺陷处的Landauer电阻率偶极子
Landauer resistivity dipole at one dimensional defect revealed via near-field photocurrent nanoscopy
AI总结：
本研究利用近场光电流纳米术的纳米级分辨率，表征单层-双层石墨烯界面这一一维缺陷处的Landauer电阻率偶极子，验证了其与载流子浓度的关联，为研究隐藏界面局域耗散提供了非侵入式方法。
摘要：
如何描述纳米尺度下的欧姆电阻这一基础问题，已由Landauer在其具有开创性的所谓Landauer电阻率偶极子理论图景中给出解答。该图景在理论上已得到充分理解，但由于需要非侵入式的局域探测手段，相关实验研究仍较为稀少。本研究利用近场光电流成像的纳米级横向分辨率，将埋层的单层-双层石墨烯界面作为Landauer电阻率偶极子的理想一维缺陷，对其开展了全面表征。通过系统调控整体载流子浓度与电流流动，我们能够检测到由一维缺陷周围的载流子积累所导致的Landauer电阻率偶极子的形成。研究发现，当费米能级接近电荷中性点时（即低空穴或电子掺杂水平下），光电流呈现出与所施加的源漏电压相同的极性，这与Landauer电阻率偶极子引发的载流子浓度变化相一致。在更高的载流子浓度下，该特征不再明显，这与我们开展的数值计算结果吻合。因此，光电流纳米术可作为一种非侵入式技术，用于研究隐藏界面处的局域耗散。
英文摘要：
The fundamental question how to describe Ohmic resistance at the nanoscale has been answered by Landauer in his seminal picture of the so-called Landauer resistivity dipole. This picture has been theoretically well understood, however experimentally there are only few studies due to the need for a non-invasive local probe. Here we use the nanometer lateral resolution of near-field photocurrent imaging to thoroughly characterize a buried monolayer - bilayer graphene interface as an ideal one dimensional defect for the Landauer resistivity dipole. Via systematic tuning of the overall charge carrier density and the current flow we are able to detect the formation of Landauer resistivity dipoles due to charge carrier accumulation around the one dimensional defects. We found that, for Fermi energy values near the charge neutrality point (i.e. at low hole or electron doping), the photocurrent exhibits the same polarity as the applied source-drain voltage, which is consistent with changes in carrier concentration induced by the Landauer resistivity dipoles. This signature is no longer evident at higher charge carrier density in agreement with the performed numerical calculations. Photocurrent nanoscopy can thus serve as non-invasive technique to study local dissipation at hidden interfaces.
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