FRG: Nanoscale Order in Amorphous Solids: Structure, Transformations, and Electronic Properties

FRG：非晶固体纳米级：结构、转变和电子特性

• 批准号: 0205858
• 负责人: John Abelson
• 金额: $ 81.89万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0205858&HistoricalAwards=false
• 关键词: FRG; Nanoscale; Order; Amorphous; Solids

This FRG project is a collaborative effort among five co-PIs, and additional collaborators with expertise in amorphous materials: preparation and analysis (Abelson, Bishop), FEM technique (Gibson, Voyles), TEM (Zuo), molecular dynamics and quantum mechanical simulations (Drabold), and statistical mechanics and topology of disordered networks (Goldbart). The project goals are to quantitatively determine the nanostructure in group IV and chalcogenide amorphous materials, and the relationship of this order with electronic properties and phase transformations. The approach is based on fluctuation electron microscopy (FEM)-a new analytical technique with the only purely structural view of MRO (medium range order) currently available. FEM in-volves a statistical analysis of the intensity scattered from nanometer-sized volumes of the sam-ple as a function of the volume, size, and scattering conditions. The project addresses nanoscale order in representative amorphous and glassy materials-amor-phous silicon and chalcogenides- which are without long range order. These materials are known to exhibit medium range order, but little is known about the nature of this ordering on the na-noscale. Medium-range order (MRO) is typically a structural correlation at length scales longer than the diameter of the third coordination shell but shorter than the scale at which ordering ap-pears as Bragg peaks in the structure factor. For amorphous silicon (a-Si), that translates to length scales of 1-4 nm. Structure at those length scales in the presence of disorder has historically been difficult to measure. Standard diffraction techniques yield little information at medium-range because of the isotropic nature of most disordered materials. The PIs have shown that strain affects small topologically crystalline regions in a-Si, rendering them not detectable in diffraction.%%% The project addresses fundamental research issues in areas of electronic materials science having technological relevance. An important feature of the project is the strong emphasis on education, and the integration of research and education. The combined resources, including experimental and theoretical methods, provide special opportunities for education and training of post doctoral associates, graduate and undergraduate students involved in highly interdisciplinary forefront research.***

这个FRG项目是五个合作PI和其他具有非晶态材料专业知识的合作者共同努力的成果：制备和分析(Abelson，Bishop)，有限元技术(Gibson，Voyles)，透射电子显微镜(Zuo)，分子动力学和量子力学模拟(Drabold)，以及无序网络的统计力学和拓扑(Goldbart)。该项目的目标是定量确定第IV族和硫化物非晶态材料中的纳米结构，以及这种有序与电子性质和相变的关系。该方法基于起伏电子显微镜，这是一种新的分析技术，具有目前可用的唯一的MRO(中程有序)的纯结构视图。有限元对样品的纳米体积的散射强度随体积、尺寸和散射条件的函数进行了统计分析。该项目致力于解决具有代表性的非晶态和玻璃材料--无形态硅和硫化物--的纳米级有序，这些材料没有长程有序。众所周知，这些材料表现出中等范围的有序性，但人们对这种无规律性的性质知之甚少。中程有序(MRO)通常是一种长于第三配位壳层直径但短于结构因子中Bragg峰的有序出现的尺度上的结构相关。对于非晶硅(a-Si)，这意味着长度尺度为1-4 nm。在无序存在的情况下，在这些长度尺度上的结构历来很难测量。由于大多数无序材料的各向同性性质，标准的衍射技术在中程产生的信息很少。PI表明，应变影响a-Si中的小的拓扑晶区，使它们在衍射中无法被检测到。%该项目解决具有技术相关性的电子材料科学领域的基础研究问题。该项目的一个重要特点是高度重视教育，并将研究与教育相结合。综合资源，包括实验和理论方法，为从事高度跨学科前沿研究的博士后助理、研究生和本科生提供了特殊的教育和培训机会。