Atomically Precise, Low-cost Manufacturing of Plasmonic Nano-Gaps for Chemical Sensing, Health Diagnostics and Optical Communication

等离子体纳米结构因其能够将光集中在较小的体积内而引起人们的极大兴趣，这将导致许多潜在的应用。虽然理论上预测最佳等离子体热点是两个金属粒子之间的间隙小于1纳米，但目前还没有可靠的制造技术来以实际成本可靠地制造出高精度和可控的等离子体热点。该奖项将通过自上而下和自下而上的过程相结合来解决这一关键障碍。图案是确定定义的，自上而下，纳米间隙由原子层沉积沉积的间隔层自下而上控制，可以以原子精度控制。这项技术可以在任意衬底上以高产量和低成本在大面积上形成金属纳米间隙。如果成功，这项技术不仅将为研究表面等离子体激元和GaP等离子体提供可靠的平台，而且还将使其在化学传感、疾病诊断和光通信方面得到应用。此外，该项目也将是一个示范展示，以激励初中生和代表不足的少数民族学生在科学、技术、工程和数学(STEM)领域学习和追求职业生涯。这一项目的成果将被整合到纳米技术课程中。虽然等离子体激元器件具有巨大的应用潜力，但目前还没有满足这些器件要求的实用制造技术。关键的困难是，对于最先进的制造技术来说，这些器件中首选的低于1 nm的金属间隙太小了。通过这个奖项，我们将通过使用可折叠纳米指模板转移印刷金属纳米间隙结构来应对这一挑战。该模板由柔性纳米手指阵列和每个纳米手指顶部的金属帽组成。整个纳米指和帽系统使用原子层沉积在间隔层上覆盖。纳米手指样品浸泡在乙醇中并风干后，毛细管力使纳米手指顶部的盖子成对坍塌。然后，通过转印将这些折叠的金属帽转移到目标基板上，并蚀刻掉间隔层。以这种方式，转印金属盖之间的间隙正好是间隔层厚度的两倍。通过研究这一过程背后的基本原理，将开发出一种变革性的金属纳米间隙制造技术。

Plasmonic nanostructures are of great interest because of their ability to concentrate light to a small volume, which can lead to many potential applications. While it is theoretically predicted that the optimal plasmonic hot spot is a gap of less than 1 nanometer between two metallic particles, there is still no manufacturing technology to reliably fabricate it with high-precision and controllability at practical cost. This award will address this key roadblock by combining top-down and bottom-up processes. Patterns are deterministically defined, top-down, and the nano-gap controlled by a spacer layer deposited by atomic layer deposition, bottom-up, which can be controlled with atomic precision. This technology can pattern metallic nano-gaps over large area on arbitrary substrates at high throughput and low cost. If successful, not only will this technology provide a reliable platform to investigate surface plasmon polaritons and gap plasmons, but it will also enable applications in chemical sensing, disease diagnosis and optical communication. Moreover, this project will also be an exemplary showcase to motivate middle and high school students and under-represented minority students to study and pursue a career in science, technology, engineering and mathematics (STEM). The findings of this project will be integrated into a nanotechnology curriculum.While plasmonic devices have great application potential, there is no practical fabrication technology that meets the requirements of these devices. The key difficulty is that the sub-1nm metallic gap preferred in these devices is too small for state-of-the-art fabrication technologies. Through this award, we will tackle this challenge by transfer-printing metallic nano-gap structures using a collapsible nano-finger template. The template consists of a flexible nano-finger array and a metallic cap on top of each nano-finger. The entire system of nano-fingers and caps is coated with a spacer layer using atomic layer deposition. After the nano-finger sample is dipped into ethanol and air-dried, the capillary force makes the caps on top of nano-fingers collapse together in pairs. Then those collapsed metallic caps are transferred to the target substrate by transfer printing, and the spacer layer is etched away. In this way the gaps between the transfer-printed metallic caps are exactly twice as thick as the spacer layer. By studying the fundamentals behind this process, a transformative metallic nano-gap manufacturing technology will be developed.