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

极小的发光器件在下一代计算和通信技术中具有潜在用途。由原子级间隙隔开的两个金属电极可以用作电子器件和纳米级光源。当电流被驱动穿过纳米间隙时，从一个电极“隧穿”到另一个电极的电子可以激发电极中的电子的集体运动，称为等离子体激元。来自连续电子的能量可以在等离子体激元和电极中积累，导致电子的稳定状态，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具有相同能量范围内的光学共振的材料，则可以强烈地修改光发射，因为能量在金属和光学材料之间来回传递。 PI建议在两个这样的耦合系统中检查光发射：作为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绝缘体（空腔）。 目标是最大化等离子体-材料能量转移的强度，检查电调谐半导体和具有非常尖锐的腔共振对光发射的影响，创建在室温下稳定工作的这种类型的发光器件，以及计数单个发射的光子以搜索光发射中的量子效应。 研究结果将通过出版物、会议演讲和PI在其博客上的可访问写作进行展示。 该项目将支持研究生和本科生研究人员的专业发展和研究培训，为熟练的技术劳动力做出贡献。 PI将参与赖斯的努力，将K12教师纳入其中，并将继续通过格拉斯科克继续教育学院向终身学习者进行公共宣传。 PI的小组已经证明，纳米级等离子体隧道结可以在电致发光过程中以高于所施加的电偏压的能量发光，该电致发光过程基于热载流子的稳态群体的等离子体辅助产生和等离子体增强复合。 在耦合到2D半导体的纳米间隙中，电致发光显示出指示强等离子体/激子耦合的峰分裂，表明这些器件是电驱动的“plexcitonic”发射器。 PI提出了一个综合的研究和教育计划，以量化和最大限度地发挥这些影响。 目标包括最大限度地提高等离子体/激子耦合的设备纳入门可调过渡金属二硫属化物;演示电致发光的等离子体纳米间隙强烈耦合到光子晶体介电腔;实现等离子体材料，允许室温操作这样的结;和使用光子计数统计检查光子聚束/反聚束，以更好地了解这些极化激元结构中的发射机制。 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，从而为优化器件结构提供关键反馈。 研究结果将通过出版物、会议演讲和PI在其博客上的可访问写作进行展示。 该项目将支持研究生和本科生研究人员的专业发展和研究培训，为熟练的技术劳动力做出贡献。 PI将参与Rice的工作，将K12教师纳入其中，并将继续通过Glasscock继续学习学校向终身学习者进行公共宣传。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.