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：与广泛使用的光电材料相比，高效光电材料仅基于低成本，无毒和丰富的IV组元素（如硅）的效率较低，因为IV组元素在电子 - 光子转换过程中的效率较低，因此具有挑战性。该项目利用了独特的纳米尺寸限制效应，并与锡合金合金生产硅锡，锗锡和硅 - 德国锡锡纳米晶体，这些纳米晶体具有出色的光吸收和发射特性。协作团队支持综合工作以及高级光学表征和理论计算，以深入了解新兴材料属性并增强光电性能。跨学科研究为从智能材料设计到设备测试领域的研究生和本科生提供了宝贵的培训。其他教育和外展活动包括K-12纳米科学外展工作，以及涉及代表性不足的高中生和女性参加夏季研究活动。技术描述：具有直接带隙的第四组基于半导体的合金是光电材料领域的长期目标。但是，这项工作主要受到材料设计和合成的挑战以及SN和GE中SN的溶解度有限的挑战。该项目利用量子限制效应和SN纳米合金方法以纳米晶体形式生产直接带隙IV组。纳米晶体表现出大小和组成可调节性，从而导致更广泛的有效带隙和优质的光物理特性。例如，通过创新的高温胶体合成方法，实现了具有良好的形态和组成的GESN，SISN和G​​ESNN合金纳米晶体，具有良好的形态和组成，远远超出了Bulk Si或ge中SN的可不用限制。在计算模拟的指导下，使用稳态和超快的吸收和发射光谱系统系统地研究了SN组成和量子限制对间接到单向带隙过渡的影响。电子结构计算用于建立对限制诱导的准直接带隙行为，组成诱导的过渡到真实直接间隙的基本理解，以及对光物理特性的表面/缺陷相关影响。通过低成本，基于溶液的加工方法，通过分子金属硫化剂连接的选定合金纳米晶体沉积在各种底物上，以证明其光电的潜力。