Electrically Driven Hot-Carrier Generation and Above-Threshold Light Emission in Plasmonic Tunnel Junctions
Electrically Driven Hot-Carrier Generation and Above-Threshold Light Emission in Plasmonic Tunnel Junctions
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DOI：
10.1021/acs.nanolett.0c02121
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发表时间：
2020-08-12
期刊：
影响因子：
10.8
通讯作者：
Natelson, Douglas
中科院分区：
文献类型：
--
作者：
Cui, Longji;Zhu, Yunxuan;Natelson, Douglas
等离子体隧道结的超阈值光发射，当发射的光子的能量明显高于入射电子的能量尺度时，引起了纳米光学领域的兴趣，但其潜在的物理原理仍然难以捉摸。我们研究了电迁移隧道结中高于阈值的光发射。我们对大量设备的测量显示出巨大的（类似于10(4)）与材料相关的光子产率（每个入射电子发射的光子）。这种戏剧性的效应不能仅仅用隧穿间隙中局域等离子体的辐射场增强来解释。有效温度超过2000 K的玻尔兹曼光谱可以很好地描述发射，并与等离子体修饰的光子态密度相耦合。有效温度在应用偏置中近似为线性，与描述由电激发局域等离子体非辐射衰变驱动的热载子动力学的理论模型一致。电生成的热载流子和非传统的光发射可以为活性光化学、光电子学和量子光学开辟道路。
Above-threshold light emission from plasmonic tunnel junctions, when emitted photons have energies significantly higher than the energy scale of incident electrons, has attracted much recent interest in nano-optics, while the underlying physics remains elusive. We examine above-threshold light emission in electromigrated tunnel junctions. Our measurements over a large ensemble of devices demonstrate a giant (similar to 10(4)) material-dependent photon yield (emitted photons per incident electrons). This dramatic effect cannot be explained only by the radiative field enhancement due to localized plasmons in the tunneling gap. Emission is well described by a Boltzmann spectrum with an effective temperature exceeding 2000 K, coupled to a plasmon-modified photonic density of states. The effective temperature is approximately linear in the applied bias, consistent with a suggested theoretical model describing hot-carrier dynamics driven by nonradiative decay of electrically excited localized plasmons. Electrically generated hot carriers and nontraditional light emission could open avenues for active photochemistry, optoelectronics, and quantum optics.