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、无毒和丰富的IV族元素（例如硅）的高效光电材料的生产具有挑战性，因为与广泛使用的光电材料相比，IV族元素在电子-光子转换过程中效率较低。本计画利用独特的奈米尺寸限制效应，并与锡合金化，以产生具有上级光吸收与发射特性之矽锡、锗锡及矽锗锡奈米晶体。合作团队支持合成工作，沿着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。其他教育和外联活动包括K-12纳米科学外联工作，以及让代表性不足的高中生和妇女参与夏季研究活动。技术描述：具有直接带隙的IV族超导体基合金是光电材料领域长期追求的目标。然而，这种努力主要受到材料设计和合成的挑战以及Sn在Si和Ge中的有限溶解度的阻碍。该项目利用量子限制效应和Sn纳米合金化方法来生产直接带隙的第IV族合金。纳米晶体表现出尺寸和组成的可调谐性，导致更宽的有效带隙和上级物理性能。例如，GeSn、SiSn和GeSiSn合金纳米晶体通过创新的高温胶体合成方法获得，其具有良好控制的形态和组成，远远超过体Si或Ge中Sn的可溶解性极限。Sn的成分和量子限制效应的间接到直接的带隙跃迁系统地研究使用稳态和超快吸收和发射光谱，通过计算机模拟的指导。电子结构的计算是用来建立一个基本的理解约束诱导准直接带隙行为，组合物诱导过渡到真正的直接间隙，和表面/缺陷相关的影响的物理性质。通过分子金属硫属化物连接的选定合金纳米晶体使用低成本、基于溶液的处理方法沉积在各种衬底上，以展示其用于光电子学的潜力。