Nanoscale electron manipulation in metals with intense THz electric fields
Nanoscale electron manipulation in metals with intense THz electric fields
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具有强太赫兹电场的金属纳米级电子操控
DOI：
10.1088/1361-6463/aaa8c7
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Katayama Ikufumi
中科院分区：
文献类型：
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作者：
Takeda Jun;Yoshioka Katsumasa;Minami Yasuo;Katayama Ikufumi
改进对纳米尺度金属电磁特性的控制对于下一代纳米电子学和等离子体设备的开发至关重要。利用太赫兹（THz）电场引起的非线性来控制电子运动是一种很有前景的方法，可以操纵金属的局部电磁特性，同时避免不良的热效应和电子跃迁。在这篇综述中，我们展示了通过强烈的太赫兹电场瞬变来操纵具有纳米结构的超薄金 (Au) 薄膜中的电子离域。随着太赫兹脉冲电场强度的增加，太赫兹频率区域的透射率在渗滤阈值附近突然下降。基于 Drude-Smith 模型，对观察到的太赫兹电场引起的非线性进行了分析。结果表明，超快电子离域是通过电子隧道穿过金纳米结构之间的狭窄绝缘桥而发生的，而不会发生材料击穿。为了定量讨论隧道过程，我们使用载流子包络相位（CEP）控制的单周期太赫兹电场进行扫描隧道显微镜。通过将 CEP 控制的太赫兹电场应用于金属纳米尖端和石墨样品之间的 1 nm 纳米间隙，可以通过量子隧道过程连贯地驱动许多电子，从纳米尖端到样品，反之亦然。所提出的概念，即由 CEP 控制的单周期太赫兹电场介导的电子隧道效应，可以促进纳米级电子操纵的发展，适用于下一代超快纳米电子学和等离子体器件。
Improved control over the electromagnetic properties of metals on a nanoscale is crucial for the development of next-generation nanoelectronics and plasmonic devices. Harnessing the terahertz (THz)-electric-field-induced nonlinearity for the motion of electrons is a promising method of manipulating the local electromagnetic properties of metals, while avoiding undesirable thermal effects and electronic transitions. In this review, we demonstrate the manipulation of electron delocalization in ultrathin gold (Au) films with nanostructures, by intense THz electric-field transients. On increasing the electric-field strength of the THz pulses, the transmittance in the THz-frequency region abruptly decreases around the percolation threshold. The observed THz-electric-field-induced nonlinearity is analysed, based on the Drude-Smith model. The results suggest that ultrafast electron delocalization occurs by electron tunnelling across the narrow insulating bridge between the Au nanostructures, without material breakdown. In order to quantitatively discuss the tunnelling process, we perform scanning tunnelling microscopy with carrier-envelope phase (CEP)-controlled single-cycle THz electric fields. By applying CEP-controlled THz electric fields to the 1 nm nanogap between a metal nanotip and graphite sample, many electrons could be coherently driven through the quantum tunnelling process, either from the nanotip to the sample or vice versa. The presented concept, namely, electron tunnelling mediated by CEP-controlled single-cycle THz electric fields, can facilitate the development of nanoscale electron manipulation, applicable to next-generation ultrafast nanoelectronics and plasmonic devices.