Electrically driven plasmonic light emitters strongly coupled to excitons and dielectric resonators

极小的发光设备在下一代计算和通信技术中具有潜在的用途。由原子尺度的间隙隔开的两个金属电极既可以用作电子设备，也可以用作纳米尺度的光源。当电流穿过纳米间隙时，从一个电极到另一个电极的电子可以激发电子在电极中的集体运动，称为等离子体。来自连续电子的能量可以在等离子体和电极中积累起来，导致电子的稳定群体，其有效温度如此之高，以至于它们在可见光范围内发光。如果纳米间隙非常接近在相同能量范围内具有光学共振的材料，那么光发射可以被强烈地改变，因为能量在金属和光学材料之间来回传递。PI建议研究两个这样的耦合系统中的光发射：充当半导体并具有发光二极管中的光学跃迁的2D材料；以及设计用于捕获特定能量的光的特殊图案化绝缘体(腔)。目标是最大限度地提高等离子体-材料能量传递的强度，检查电子调谐半导体并具有非常尖锐的腔共振对光发射的影响，创造在室温下稳定工作的这种类型的发光设备，并计算单个发射的光子以寻找光发射中的量子效应。结果将通过出版物、会议演讲和PI在他的博客上发表的易读文章来展示。该项目将支持研究生和本科生的专业发展和研究培训，为培养一支熟练的技术队伍做出贡献。PI将参与莱斯的工作，吸收K12教师，并将继续通过Glasscock继续学习学校向公众推广终身学习者。Pi的团队已经证明，在基于等离子体辅助产生和等离子体增强的稳态热载流子复合的电致发光过程中，纳米级的等离子体隧道结可以在施加偏压以上的能量处发光。在与2D半导体耦合的纳米GaP中，电致发光显示出强烈的等离子体激子/激子耦合的峰分裂，表明这些器件是电驱动的“激子”发射体。PI提出了一个综合的研究和教育计划，以量化和最大化这些影响。目标包括在包含栅极可调谐过渡金属二卤化物的器件中最大化等离子体激子/激子耦合；展示强耦合到光子晶体介质腔的等离子体纳米GaP中的电致发光；在允许室温操作的等离子体材料中实现这种连接；以及使用光子计数统计来检查光子聚束/反聚束，以更好地理解这些极化子结构中的发射机制。PI的研究生和本科生研究人员团队将与理论家合作对这些系统进行建模，实现关键反馈，以优化设备结构。结果将通过出版物、会议演讲和PI在他的博客上发表的易读文章来展示。该项目将支持研究生和本科生的专业发展和研究培训，为培养一支熟练的技术队伍做出贡献。该奖项反映了NSF的法定使命，并通过基金会的知识价值和更广泛的影响审查标准进行评估，被认为是值得支持的。

Extremely small light emitting devices are of potential use in next-generation computing and communications technologies. Two metal electrodes separated by an atomic-scale gap can function as both an electrical device and a nanoscale light source. When a current is driven across the nanogap, the electrons that “tunnel” from one electrode to the other can excite collective motions of the electrons, called plasmons, in the electrodes. Energy from successive electrons can build up in the plasmons and the electrodes, leading to a steady-state population of electrons with an effective temperature so high that they glow in the visible range. If the nanogap is very close to materials with optical resonances in that same energy range, then the light emission can be strongly modified, as energy is transferred back and forth between the metal and the optical materials. The PI proposes to examine light emission in two such coupled systems: 2D materials that act as semiconductors and have the kind of optical transitions in light emitting diodes; and special patterned insulators (cavities) that are designed to trap light at specific energies. The goals are to maximize the strength of the plasmon-material energy transfer, to examine the effect on light emission of electrically tuning the semiconductor and having very sharp cavity resonances, to create light emitting devices of this type that function stably at room temperature, and to count individual emitted photons to search for quantum effects in the light emission. Results will be presented through publications, conference talks, and accessible writing by the PI on his blog. This project will support the professional development and research training of graduate students and undergraduate researchers, contributing to a skilled technological workforce. The PI will participate in Rice efforts incorporating K12 teachers and will continue public outreach to lifelong learners through the Glasscock School of Continuing Studies. The PI’s group has demonstrated that nanoscale plasmonic tunnel junctions can emit light at energies above the applied electrical bias in an electroluminescent process based on the plasmon-assisted generation and plasmon-enhanced recombination of a steady-state population of hot carriers. In nanogaps coupled to 2D semiconductors, the electroluminescence shows peak splittings indicative of strong plasmon/exciton coupling, showing that these devices are electrically driven “plexcitonic” emitters. The PI proposes an integrated research and education program to quantify and maximize these effects. Goals include maximizing the plasmon/exciton coupling in devices incorporating gate-tunable transition metal dichalcogenides; demonstrating electroluminescence in plasmonic nanogaps strongly coupled to photonic crystal dielectric cavities; implementing such junctions in plasmonic materials that allow room temperature operation; and using photon counting statistics to examine photon bunching/antibunching, to better understand emission mechanisms in these polaritonic structures. The PI’s team of graduate and undergraduate researchers will collaborate with theorists in modeling of these systems, enabling critical feedback for optimization of device structures. Results will be presented through publications, conference talks, and accessible writing by the PI on his blog. This project will support the professional development and research training of graduate students and undergraduate researchers, contributing to a skilled technological workforce. The PI will participate in Rice efforts incorporating K12 teachers and will continue public outreach to lifelong learners through the Glasscock School of Continuing Studies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.