Low-Dimensional Si-Sn and Si-Ge-Sn Nanoalloys as High-Efficiency, Direct-gap Nanostructures for Visible to Infrared Optoelectronics.

低维 Si-Sn 和 Si-Ge-Sn 纳米合金作为高效、直接带隙纳米结构，用于可见光到红外光电器件。

• 批准号: 2211606
• 负责人: Indika Arachchige
• 金额: $ 49.99万
• 依托单位: Virginia Commonwealth University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2211606&HistoricalAwards=false
• 关键词: Low; Dimensional; Si; Sn; Ge

Non-technical Description: Developing high-efficiency light emitters from earth abundant elements is imperative to replace rare and expensive materials currently used in optical and electronic technologies. The prospective low-cost and non-toxic candidates such as silicon, however, show extremely low electricity to light conversion efficiency in their conventional arrangement. This project integrates the unique quantum effects in nanoscale silicon and tin alloying to produce silicon-tin and silicon-germanium-tin nanoparticles with size and composition tunable superior light absorption and emission properties for visible to infrared applications. The research team combines the material synthesis efforts with computational calculations and advanced optical and structural characterizations to garner a comprehensive understanding of the physical and optical properties and stability of nanoscale alloys. The collaborative nature of this research provides multidisciplinary training and mentoring of graduate and undergraduate students, to develop skills in materials design and synthesis, computational chemistry, nanoscience, and advanced optical spectroscopy. The summer outreach to Richmond Public Schools exposes K-12 students to cutting-edge materials research projects and develops age-appropriate materials science curricular modules, impacting hundreds of underrepresented minority students. Technical Description: Group IV semiconductor alloys that show high efficiency direct-gap emission have gained exceptional interest for realizing Si-based optoelectronic technologies. However, the narrow energy gaps and the extremely low solubility of Sn in Si and Ge hindered their fabrication and widespread application in visible to infrared optoelectronic studies. This project exploits the concerted influences of quantum confinement effects, Sn nano-alloying, and solution-phase synthesis to produce metastable Si-Sn and Si-Ge-Sn alloys and quantum dots (QDs) with size and composition tunable direct energy gaps and superior absorption and emission properties across visible to infrared spectrum. A series of monodisperse alloys having various sizes and compositions are produced by innovative colloidal chemistry methods. The influences of Sn alloying and quantum confinement on optical properties are thoroughly and systematically probed via steady-state and time-resolved photoluminescence and pump/probe transient absorption spectroscopy, guided by first-principles electronic structure and thermodynamic stability calculations. Experiments are designed to probe confinement- and composition-induced direct-gaps of silicon, dark vs. bright excitonic states and their dependence on nanocrystal size and composition, and carrier relaxation mechanisms involving QD core, surface, and their hybrid states to optimize the radiative efficiency. These later efforts along with solution processing and high thermal and optical stability of nanocrystal alloys enable the future design of high-efficiency, silicon-based optoelectronics.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：从地球丰富的元素中开发高效的光发射器对于取代当前在光学和电子技术中使用的稀有且昂贵的材料。然而，前瞻性的低成本和无毒候选者（例如硅）在其常规排列中表现出极低的电力到光转化效率。该项目集成了纳米级硅和锡合金中的独特量子效应，以产生硅锡和硅 - 德国锡锡纳米颗粒，具有尺寸和可调性的较高光吸收和发射特性，可与红外应用可见。研究团队将材料合成工作与计算计算以及先进的光学和结构特征相结合，以全面了解纳米级合金的物理和光学特性以及稳定性。这项研究的协作性质提供了研究生和本科生的多学科培训和指导，以发展材料设计和合成，计算化学，纳米科学和先进的光学光谱方面的技能。夏季向里士满公立学校的宣传使K-12学生接触了尖端的材料研究项目，并开发了适合年龄的材料科学课程模块，影响了数百名代表性不足的少数族裔学生。技术描述：IV组半导体合金表现出高效率直接隙排放已引起实现基于SI的光电技术的极大兴趣。但是，SN和GE中SN的狭窄能量差距和极低的溶解度阻碍了其在红外光电研究中可见的广泛应用。该项目利用了量子限制效应，SN纳米合金和溶液相合成的一致影响，以产生可稳定的SI-SN和SI-GE-SN合金和量子点（QDS），具有可调的直接能量隙，较高的吸收和出色的吸收和发射性能，以及可见的基础范围内的跨越基础。创新的胶体化学方法产生了一系列具有各种尺寸和组成的单分散合金。通过稳态和时间分辨的光致发光以及泵/探针瞬态吸收光谱，通过第一原则电子结构和热力学稳定性计算引导，通过稳态和时间分辨的光致发光以及泵/探针瞬态吸收光谱对光学特性的影响进行了彻底和系统的探测。实验旨在探测硅，深色与明亮的激子状态的限制和组成诱导的直接间隙及其对纳米晶体大小和组成的依赖，以及涉及QD核心，表面及其混合状态的载体弛豫机制，以优化放射性效率。这些后来的努力以及纳米晶体合金的溶液处理以及高热和光学稳定性，可以使未来的高效设计设计，基于硅的光电子。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绩效和更广泛影响的评估来通过评估来获得支持的。