SusChEM: Synthesis and Structure-Property Elucidation of Direct-Bandgap Group IV Alloy Nanocrystals for Optoelectronic Applications

SusChEM：用于光电应用的直接带隙 IV 族合金纳米晶体的合成和结构性能阐明

• 批准号: 1506595
• 负责人: Indika Arachchige
• 金额: $ 38.91万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506595&HistoricalAwards=false
• 关键词: SusChEM; Synthesis; Structure; Property; Elucidation

Non-technical Description: The production of high-efficiency optoelectronic materials based solely on low-cost, non-toxic, and abundant Group IV elements such as silicon is challenging as Group IV elements are less efficient in electron-photon conversion process compared to the widely used optoelectronic materials. This project utilizes the unique nanoscale size confinement effects and alloying with tin to produce silicon-tin, germanium-tin, and silicon-germanium-tin nanocrystals that exhibit superior light absorption and emission properties. The collaborative team supports the synthetic efforts along with advanced optical characterization and theoretical calculations to garner a deep understanding of the emerging materials properties and enhance the optoelectronic performance. The interdisciplinary research provides valuable training to the graduate and undergraduate students in the areas from smart material design to device testing. Other education and outreach activities include K-12 nanoscience outreach efforts and involving the under-represented high school students and women in summer research activities. Technical Description: Group IV semiconductor-based alloys with a direct bandgap are a long-sought goal in the field of optoelectronic materials. However this effort has been hindered primarily by the challenges in material design and synthesis, as well as the limited solubility of Sn in Si and Ge. This project utilizes both the quantum confinement effect and the Sn nano-alloying approach to produce direct bandgap Group IV alloys in nanocrystal form. The nanocrystals exhibit size and composition tunability that leads to wider effective bandgaps and superior photophysical properties. For example, GeSn, SiSn, and GeSiSn alloy nanocrystals with well controlled morphology and composition, far beyond the miscibility limit of Sn in bulk Si or Ge, are achieved via an innovative high-temperature colloidal synthesis method. Sn composition and quantum confinement effects on the indirect-to-direct bandgap transition are systematically investigated using steady-state and ultrafast absorption and emission spectroscopy, guided by computational simulations. The electronic structure calculations are used to establish a fundamental understanding of confinement-induced quasi direct bandgap behavior, composition-induced transition to true direct-gap, and surface/defect related effects on photophysical properties. Selected alloy nanocrystals linked by molecular metal chalcogenides are deposited on various substrates using low-cost, solution-based processing methods to demonstrate their potential for optoelectronics.

非技术描述：仅基于低成本、无毒且丰富的硅等第四族元素生产高效光电材料具有挑战性，因为与硅等第四族元素相比，第四族元素的电子-光子转换过程效率较低。广泛应用的光电材料。该项目利用独特的纳米级尺寸限制效应和与锡的合金化来生产具有优异的光吸收和发射特性的硅-锡、锗-锡和硅-锗-锡纳米晶体。该协作团队支持合成工作以及先进的光学表征和理论计算，以深入了解新兴材料的特性并提高光电性能。跨学科研究为研究生和本科生提供了从智能材料设计到设备测试等领域的宝贵培训。其他教育和推广活动包括 K-12 纳米科学推广活动以及让代表性不足的高中生和女性参与夏季研究活动。技术描述：具有直接带隙的IV族半导体基合金是光电材料领域长期以来寻求的目标。然而，这一努力主要受到材料设计和合成方面的挑战以及 Sn 在 Si 和 Ge 中溶解度有限的阻碍。该项目利用量子限制效应和锡纳米合金方法来生产纳米晶体形式的直接带隙 IV 族合金。纳米晶体表现出尺寸和成分的可调性，从而实现更宽的有效带隙和优异的光物理性质。例如，通过创新的高温胶体合成方法获得了形态和成分得到良好控制的GeSn、SiSn和GeSiSn合金纳米晶体，远远超出了Sn在块状Si或Ge中的混溶极限。在计算模拟的指导下，使用稳态和超快吸收和发射光谱系统地研究了锡成分和量子限制对间接到直接带隙跃迁的影响。电子结构计算用于建立对限制引起的准直接带隙行为、成分引起的到真正直接带隙的转变以及表面/缺陷对光物理性质的相关影响的基本理解。使用低成本、基于溶液的加工方法将由分子金属硫族化物连接的选定合金纳米晶体沉积在各种基材上，以展示其光电潜力。