横向隧穿电子激发局域表面等离激元发光行为研究

Plasmon-mediated luminescence induced by tunneling electrons is an interesting and complex physical phenomenon, which can be potentially used for electrical excitation of surface plasmons and nanoscale laser sources. In the past several decades, this luminescent phenomenon has been extensively investigated in metal-insulator-metal (MIM) sandwich devices and scanning tunneling microscope (STM) configurations. In-plane lateral tunneling junction, due to its better design flexibility, may promise several advantages in terms of luminescence tunability, luminescence efficiency, and on-chip integration. However, due to the difficulty of device fabrication, the luminescence induced by lateral tunneling electrons has never been investigated and reported. In this project, we will firstly develop new techniques to fabricate in-plane lateral tunneling junctions, based on which we will have a systematical and in-depth study on the localized-plasmon-mediated luminescence induced by lateral tunneling electrons. We will explore how the luminescence spectra and efficiency are determined and modulated by the tunneling-junction parameters such as electrode geometry, electrode dimension, applied voltage and junction barrier. Besides, we will further investigate the internal relationship between the luminescence spectra and inelastic electron tunneling spectra. Based on this project, we expect to discover the key role of localized plasmons in determining the luminescence in lateral tunneling junctions. In addition, we aim to understand the evolution dynamics and energy inter-conversion mechanism between the elementary excitations including tunneling electrons, plasmons, photons and phonons involved in this luminescent phenomenon. Based on above understandings, we will try to establish a physical model to quantitatively describe this process, which we hope will help us to design high efficiency plasmon and photon nanosources that can be excited by electrical nanocircuits.

隧穿电子诱导等离激元共振进而辐射发光现象蕴藏着丰富的物理内涵并有望应用于电激发等离激元和纳米光源器件，自被发现以来在薄膜型MIM及STM隧道结体系中得到了广泛研究。面内横向隧道结具有更好的可设计性，在发光调控、发光效率以及片上集成等方面具有众多潜在优势。然而，由于器件加工困难，其发光现象尚未得到研究和报道。本项目拟以可控构筑由金属纳米结构电极对组成的横向隧道结为突破口，对横向隧穿电子激发局域等离激元共振并辐射发光的现象进行系统而深入的研究。项目将探索该现象中发光光谱和发光效率与隧道结电极形貌、尺寸、外加电压及结势垒等参数之间的关系及其调控规律，挖掘发光谱与电子隧道谱的内在联系，揭示横向隧穿结发光过程中局域等离激元共振所扮演的关键角色，阐明其中隧穿电子、等离激元及光子等元激发之间的动力学演化过程及能量转移转化机制，并建立相关物理模型，为开发高效电激发等离激元源和纳米光源提供理论和实验基础。

隧穿电子诱导等离激元共振进而辐射发光的现象蕴藏着丰富的物理内涵并有望应用于电激发等离激元和纳米光源器件。面内纳米间隙横向隧道结具有更好的可设计性，在发光调控、发光效率及片上集成等方面具有潜在优势，但其研究面临高品质等离激元发光纳米结构及跨尺度有源器件加工难、单粒子尺度光电联用光谱测试等挑战。本项目针对上述难题，以可控构筑高品质横向隧穿等离激元器件及其光电联用光谱测试为目标，主要研究内容包括：（1）等离激元纳米间隙隧穿结构的优化设计与仿真；（2）高品质等离激元纳米结构及跨尺度金属电极的可靠加工；（3）单粒子尺度光电联用光谱测试装备开发；（4）横向隧道结体系的发光机理及应用研究。项目自执行以来，相关成果共发表SCI论文35篇，包括光学领域公认的顶级期刊论文Nano Letters 3篇，ACS Nano 2篇，Light: Science & Applications 1篇，相关技术申报国家发明专利4项，受邀在国内外学术会议上做特邀报告15次，支持15名研究生和博士后进行相关工作。取得重要进展包括：（1）发展了一种拓扑优化方法，可根据特定功能，实现等离激元发光纳米结构的优化设计；（2）发展了系列创新制造工艺，实现了高品质等离激元纳米结构的加工；（3）提出了三类电子束/离子束轮廓加工新工艺，可直接制造跨尺度电极，并应用于有源器件的定制；（4）基于共聚焦显微镜，设计并成功搭建了单粒子光电联用光谱测试系统；（5）基于项目成果，探索了纳米光学结构在单分子探测、FP腔阵列构筑、超表面结构加工方面的创新应用。本项目一方面开发了多种具有隧穿尺度特征尺寸的跨尺度纳米间隙电极的制造方法，为后续进一步制造横向隧穿光电器件提供了加工工艺，另一方面开发了一套用于单粒子等离激元纳米结构光谱研究的光电联用测试装备，为后续进一步的深入机理研究提供了测试手段。项目的顺利实施为等离激元纳米结构有源器件的开发提供了技术积累。