Collaborative Research: OP: Transition Metal Alloys: Emergent Properties for Near-Infrared Hot-Carrier Optoelectronics

合作研究：OP：过渡金属合金：近红外热载流子光电器件的新兴特性

• 批准号: 2114304
• 负责人: Kevin McPeak
• 金额: $ 42.22万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2114304&HistoricalAwards=false
• 关键词: Collaborative; Research; OP; Transition; Metal

Modern electronics are based on charge transport by electrons and holes in semiconductors. The behavior of carriers with excess energy, called “hot” carriers, is of particular interest. Hot-carrier materials have a broad range of applications including hydrogen production, local heating for nanotherapeutics, and photodetectors. Hot-carrier photodetectors show great promise due to their tunability and ultrafast response. Unfortunately, the low efficiencies of hot carrier materials have made them impractical for use in devices. The PIs have recently discovered that alloys of noble metals and transition metals have the potential to efficiently generate long-lived hot carriers, a breakthrough in the field. This project will investigate transition metal alloys and their ability to generate and efficiently transport above-equilibrium “hot” electrons and holes in an optoelectronic devices. The proposed work is expected to provide transformational advances in the efficiency of near-infrared hot-carrier photodetectors. Education and outreach for this project will teach students through research activities and will expose people of diverse ages and backgrounds to the concepts of alloying, metal-optics, and optoelectronics. The research team will involve graduate and undergraduate students to perform this research in the team's laboratories and partner with local middle and high schools to involve 6th through 12th-grade students in hands-on scientific work. High school students from local Baton Rouge high schools will participate in annual summer in-lab residency programs and middle-school students in the Philadelphia area will participate in a solar race by building, testing, and racing shoebox-sized solar powered cars. This project is jointly funded by the Electronic and Photonic Materials (EPM) and Metals and Metallic Nanostructures (MMN) programs of the Division of Materials Research.Hot-carrier generation in metals is a promising route to convert photons into electrical charges for near-infrared (NIR) optoelectronic devices. Hot-carrier optoelectronic devices offer below-bandgap charge generation, ultrafast response times, and spectral and polarization control. These features are expected to result in transformative advances in optoelectronics. However, current hot-carrier devices exhibit low efficiencies due to poor carrier generation and collection rates. Photoexcited metals can generate hot carriers via interband, intraband, and plasmon-assisted Landau damping. While noble metals have been extensively explored for generating hot carriers via interband transitions, NIR photons do not have enough energy to overcome their interband energy threshold. Intraband- and plasmon-driven hot-carrier generation can occur at these lower excitation energies, but only if additional momentum is provided. The research team hypothesizes that band hybridization in transition metal alloys will result in emergent properties and new pathways for NIR hot-carrier generation. The team recently reported that, when photoexcited at 1550 nm, an Au50Pd50 alloy having NIR accessible interband transitions exhibited 20-fold more 0.8 eV hot holes than pure Au and 3-times longer lifetime than pure Pd. The team will build on this exciting result by pursuing the following specific aims: 1). Use first-principles simulations to determine candidate transition metal alloys that excel at hot-carrier generation in the NIR, 2). Deposit alloy films via thermal co-evaporation and use resonant synchrotron-based photoemission to verify the predicted electronic properties, 3). Determine the effect alloying has on carrier lifetime using transient absorption spectroscopy and 4). Fabricate below-bandgap photoconductors using alloy absorbers and characterize their electrical response. The research team is well suited to pursue these aims with expertise in alloy theory, photoemission, metal film growth, device fabrication, and ultrafast spectroscopy. Transition metal alloys offer an exciting palette for synthesizing new hot-carrier materials, and the team is well-positioned to investigate their structure-function relationship.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.

现代电子设备基于通过电子设备和半导体孔的电荷传输。具有多余能量的载体（称为“热”载体）的行为特别令人感兴趣。热载体材料具有广泛的应用，包括氢生产，纳米疗法的局部加热和光电遗传能。热载体光电探测器由于其可线性和超快响应而显示出很大的希望。不幸的是，热载体材料的低效率使它们在设备中不切实际。 PI最近发现，高贵金属和过渡金属的合金有可能有效产生长寿命的热载体，这是该领域的突破。该项目将研究过渡金属合金及其在光电设备中产生高于平衡的“热”电子和孔的能力。预计拟议的工作将在近红外热携带者光电探测器的效率方面提高转化。该项目的教育和外展活动将通过研究活动来教学学生，并将使年龄和背景的人们了解合金，金属镜和光电子学的概念。研究团队将涉及研究生和本科生在团队的实验室中进行这项研究，并与当地的中学和高中合作，参与6至12年级的学生进行动手科学工作。来自当地巴吞鲁日高中的高中学生将参加年度夏季居住居住计划，费城地区的中学学生将通过建造，测试和赛车鞋盒大小的太阳能汽车参加太阳能竞赛。该项目由电子和光子材料（EPM）以及材料研究部的金属和金属纳米结构（MMN）共同资助。金属中的Hot-Carrier生成是一种有望将照片转换为近红外（NIR）光电设备的电荷的途径。热载波光电设备可提供低于频道电荷的产生，超快响应时间以及光谱和极化控制。这些特征有望导致光电学的变革性进步。但是，由于携带者的产生和收集率差，当前的热载体设备的效率较低。光激发的金属可以通过侧带，内部和等离子辅助的Landau阻尼产生热载体。尽管已经广泛探索过贵金属，以通过带间的过渡产生热载体，但NIR照片没有足够的能量来克服其带的能量阈值。在这些较低的兴奋能量下，可以发生内标和等离子驱动的热载体生成，但前提是提供额外的动量。研究团队假设过渡金属合金中的带杂交将导致新兴的特性和NIR热载体生成的新途径。该团队最近报道说，当光激发1550 nm时，Au50pd50合金具有NIR可访问的频带过渡，比纯au比纯PD更长的0.8 eV热孔，比纯PD多20倍。团队将通过追求以下特定目标来基于这个令人兴奋的结果：1）。使用第一原理模拟来确定在NIR中在Hot-Carrier Generation（2）中出色的候选过渡金属合金，2）。通过热共蒸发沉积合金膜，并使用基于谐振的同步加速器的光发射来验证预测的电子特性，3）。使用瞬态抽象光谱和4）确定合成对载体寿命的效果。使用合金吸收器制造低于带gap的光电导体，并表征其电响应。研究团队非常适合通过合金理论，光发射，金属膜增长，装置制造和超快光谱方面的专业知识来追求这些目标。过渡金属合金提供了一个令人兴奋的调色板，可用于合成新的热载体材料，并且该团队良好地调查了他们的结构功能关系。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估值得支持。