Remote Excitation of Hot Electrons via Propagating Surface Plasmons
Remote Excitation of Hot Electrons via Propagating Surface Plasmons
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DOI：
10.1021/acs.jpcc.9b01174
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发表时间：
2019-04-18
影响因子：
3.7
通讯作者：
Natelson, Douglas
中科院分区：
文献类型：
--
作者：
Evans, Charlotte I.;Natelson, Douglas
等离子体纳米结构中的高效热电子产生特别令人感兴趣。由于直接吸收和加热，区分热载流子产生和其他竞争效应可能具有挑战性。在这里，我们报告的开路光电压在薄膜金纳米结构的照明位置的函数的研究。比较之间的直接照明的纳米线收缩或电迁移隧道结和远程激发通过使用光栅在周围的电极激发传播表面等离子体激元（SPPs）。光电压响应在连续的纳米线收缩占主导地位的光热电效应，与光栅照明表明，它是可能的，以实现一个非平凡的温度分布在激发。隧穿间隙的直接照明先前已经证明了由于热电子隧穿而增强的光电压。我们再次确认这一点，并发现通过照射后的光栅电迁移产生的光电压增强到一个因素的100相比，他们的预迁移值。在光栅处具有照明的信号的偏振依赖性和极性提供了这样的证据，即SPP与差距处的局部等离子体振子模式耦合，经由等离子体振子衰减产生热电子电流，并且相应的开路电压发展为强制无净电流的开路条件。在这样的测量中的变化示出了SPP局部模式耦合的结的结构细节的敏感性。
Efficient hot electron generation in plasmonic nanostructures is of particular interest. Distinguishing between hot carrier generation and other competing effects due to direct absorption and heating can be challenging. Here, we report a study of the open-circuit photovoltage in thin-film gold nanostructures as a function of illumination position. Comparison is made between direct illumination of a nanowire constriction or electromigrated tunneling junction and remote excitation via the use gratings in the surrounding electrode to excite propagating surface plasmon polaritons (SPPs). Photo voltage response in continuous nanowire constrictions is dominated by photo-thermoelectric effects, with grating illumination demonstrating that it is possible to achieve a nontrivial temperature distribution at excitation. Direct illumination of tunneling gaps had previously demonstrated enhanced photovoltages due to hot electron tunneling. We reconfirm this and find that the photovoltages generated by illuminating the gratings after electromigration are enhanced up to a factor of 100 compared to their premigration values. The polarization dependence and polarity of the signal with illumination at the grating provide evidence that the SPPs couple with local plasmon modes at the gap, producing hot electron current via plasmon decay, and a corresponding open-circuit voltage develops to enforce the open-circuit condition of no net current. Variations in such measurements show the sensitivity of SPP-local mode coupling to the structural details of the junctions.