Collaborative Research: Atomic-Scale Hybrids, Tuning the IR Dielectric Function through Superlattice Design

合作研究：原子级混合体，通过超晶格设计调节红外介电函数

• 批准号: 1905295
• 负责人: Prineha Narang
• 金额: $ 9万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905295&HistoricalAwards=false
• 关键词: Collaborative; Research; Atomic; Scale; Hybrids

Non-Technical Description: The infrared spectral range offers a wealth of technological opportunities, including thermal imaging, ability to see through dust or clouds, chemical identification for medical diagnostics and hazard identification, to name a few. Unlike the visible spectral range where materials such as glass provide exceptionally high performance at extremely low cost, the infrared optical components are typically sensitive to water, opaque in the visible, expensive and/or brittle. Thus, identifying alternative materials or material platforms that can provide the basis of next generation infrared optics and light sources is highly desired. Within the infrared, many polar materials, such as silicon carbide, exhibit crystal vibrations that can be excited using light. This provides opportunities to compress long-wavelength infrared light to nanometer scale lengths, offering the potential to significantly reduce the size of infrared optics. However, these crystal vibrations are material specific and thus, finding the right material in the desired infrared frequency range is challenging. This project investigates novel hybrid materials composed of altering stacking thin layers with potential to modify their crystal vibrations in an effort to change its corresponding infrared properties. The collaborative research seeks to understand how these vibrations are influenced when the layer thickness is reduced to atom-scale thicknesses, and involves a multidisciplinary team of a material scientist, physicist and mechanical engineer to aid in realizing designer infrared materials deemed 'crystalline hybrids'. The project trains graduate and undergraduate students in semiconductor growth, infrared spectroscopy and characterization and theoretical descriptions of complex solids.Technical Description: This project seeks to develop a new class of materials called Crystalline Hybrids (XHs) that offers the promise for realizing user-defined infrared (IR) optical materials. These novel materials can serve as the basis of next generation IR optical components, sources and detector elements. A primary research goal of this collaborative program is to discover theory-guided principles for the rational design of XHs to meet a given application space. The XH approach seeks to modify polar optic phonons within atomically thin layers comprising a multilayered superlattice. Within these structures, the layer thicknesses will be less than the phonon mean-free-path, resulting in quantum confinement and frequency tuning of the vibrational state. Furthermore, the modified bonding at the multiple interfaces within the superlattice structures introduce new interfacial phonons. These modified phonon properties directly influence the infrared response of the material, as it is optic phonons that dominate the IR behavior of polar crystals. The research is focused on superlattices comprised of the near-lattice matched III-V semiconductors InAs, GaSb and AlSb, which eliminate external effects like strain and allow well-controlled experiments to be performed. The project involves a diverse group of graduate and undergraduate students who are trained in the basics of semiconductor growth, IR spectroscopy, theory and first-principles calculations of nanomaterials, enabling them to work at the frontiers of nanophotonics research. The collaboration between material scientists, physicists and engineers broadens the impact of this work.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.

非技术描述：红外光谱范围提供了大量的技术机会，包括热成像，通过灰尘或云看到的能力，医学诊断和危害识别的化学识别，仅举几例。与可见的光谱范围不同，诸如玻璃等材料以极低的成本提供了出色的性能，红外光学组件通常对水敏感，可见，昂贵和/或脆弱。因此，高度需要识别可以提供下一代红外光学和光源基础的替代材料或材料平台。在红外线中，许多极性材料，例如碳化硅，都会表现出可以使用光激发的晶体振动。这提供了压缩长波长红外光到纳米尺度长度的机会，从而有可能显着降低红外光学元件的大小。但是，这些晶体振动是特定于物质的，因此，在所需的红外频率范围内找到合适的材料是具有挑战性的。该项目研究了新型混合材料，该材料由改变堆叠薄层的薄层组成，并可能改变其晶体振动，以改变其相应的红外特性。协作研究试图了解当层厚度降低为原子尺度厚度时，如何影响这些振动，并涉及一支由物质科学家，物理学家和机械工程师组成的多学科团队，以帮助实现被认为是“结晶混合动力”的设计师红外材料。该项目培训了半导体增长，红外光谱和表征以及复杂固体的理论描述的毕业生和本科生。技术描述：该项目旨在开发一种新的称为Crystalline Hybrids（XHS）的材料，这些材料为实现用户定义的红外（IR）光学材料提供了希望。这些新型材料可以作为下一代IR光学组件，源和检测器元素的基础。该协作计划的主要研究目标是发现XHS合理设计的理论指导原则，以满足给定的应用程序空间。 XH方法旨在修改包含多层超晶格的原子薄层中的极性光子声子。在这些结构中，层厚度将小于无声子平均路径，从而导致振动状态的量子限制和频率调整。此外，在超晶格结构内的多个接口处进行了修改的键，引入了新的界面声子。这些修饰的声子特性直接影响材料的红外响应，因为是主导极性晶体的IR行为。该研究集中在由近晶格匹配的III-V半导体INAS，GASB和ALSB组成的超级晶格上，这些晶格消除了诸如应变之类的外部效应，并允许进行良好的控制实验。该项目涉及一组多样化的研究生和本科生，他们接受了半导体生长，红外光谱，理论和第一原则计算纳米材料的基础知识，使他们能够在纳米摄氏研究的边界工作。物质科学家，物理学家和工程师之间的合作扩大了这项工作的影响。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估标准来评估的。