Materials World Network: Terahertz Spectroscopy of Modulation Doped Si and SiGe Nanostructures

材料世界网：调制掺杂硅和硅锗纳米结构的太赫兹光谱

• 批准号: 0601920
• 负责人: James Kolodzey
• 金额: --
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-15 至 2009-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0601920&HistoricalAwards=false
• 关键词: Materials; World; Network; Terahertz; Spectroscopy

This Materials World Network award to University of Delaware is for experimental and theoretical studies on shallow dopants in modulation-doped silicon and silicon-germanium nanostructures. Dopants in nanostructures have unusual behavior because of complex materials interactions between the composition, interfaces, and the method of synthesis. Strain in nanostructures can push the dopant levels into the band creating a resonant state with enhanced luminescence, and the modulation doping of nanostructures may produce novel functionality as it has done for bulk materials and thin films. The properties of dopants in nanostructures have not been well understood, however, and there are fundamental questions regarding the mechanisms that affect the energy states and transport of charge carriers. As a result, it has been difficult to distinguish between fundamental and process related influences. To achieve a greater understanding, the investigators will study radiative terahertz transitions between different localized and resonant states of impurities and continuum states, as well as carrier transport phenomena. The energy spectra, density of states, capture and ionization rates of two dimensional impurity states split by strain and space quantization, and the probabilities of optical transitions will be obtained experimentally and theoretically. The growth techniques will be molecular beam epitaxy and chemical vapor deposition, guided by experiments and theory to uncover fundamental principles. The characterization techniques will be temperature dependent terahertz electroluminescence spectroscopy and current versus voltage measurements. The results of experiments will be compared with simulations and modeling interactively, to refine theories and to guide the choice of growth conditions for creating doped nanostructures with specific parameters. The approaches planned here can yield new information on the spectral features of impurity transitions and states in SiGe nanostructures, and the materials parameters that affect the radiative emission frequency and intensity. A special objective is to investigate the conditions for, and origin of population inversion in impurities states, and to clarify these mechanisms in modulation doped Si and SiGe structures. Possible technological consequences for this research would be to guide the selection of dopants as device sizes shrink, and to identify phenomena for new families of devices based on radiative transitions in dopants. The project will be carried out in collaboration with Russian scientists at Ioffe Physico-Technical Institute (St. Petersburg), and the Institute of Radioengineering and Electronics (Moscow). The assembled team has complementary expertise and facilities to conduct the proposed research. The award will provide opportunities for education and discovery in this international collaboration by students and junior and senior researchers. This collaborative research between scientists at University of Delaware and Russia could lead to a greater understanding of the synthesis and properties of doped SiGe nanostructures, and the identification of mechanisms that underlie carrier transport and radiative transitions. The education and training of students in a technologically important materials project is a pivotal aspect of the proposed international collaboration. In addition the results of this program will be incorporated into courses at the University of Delaware, and highlights of research will be featured on a web page designed to provide educational information on nanostructures to students and the general public.

该材料世界网络奖授予特拉华大学，用于对调制掺杂硅和硅锗纳米结构中的浅掺杂剂进行实验和理论研究。纳米结构中的掺杂剂由于其组成、界面和合成方法等复杂的材料相互作用而具有不同寻常的行为。纳米结构中的应变可以将掺杂水平推入能带，从而产生共振状态，从而增强发光，纳米结构的调制掺杂可能会产生新的功能，就像它在块状材料和薄膜中所做的那样。然而，掺杂剂在纳米结构中的性质尚未被很好地理解，并且关于影响载流子的能量状态和输运的机制存在一些基本问题。因此，很难区分基本影响和与过程有关的影响。为了获得更好的理解，研究人员将研究杂质和连续态的不同局域和共振态之间的辐射太赫兹跃迁，以及载流子输运现象。通过实验和理论得到了二维杂质态的能谱、态密度、捕获率和电离率，以及由应变和空间量子化分裂的光跃迁概率。在实验和理论的指导下，以分子束外延和化学气相沉积为生长技术，揭示其基本原理。表征技术将是温度相关的太赫兹电致发光光谱和电流与电压的测量。实验结果将与模拟和建模进行交互比较，以完善理论并指导选择具有特定参数的掺杂纳米结构的生长条件。本文计划的方法可以提供关于SiGe纳米结构中杂质跃迁和状态的光谱特征以及影响辐射发射频率和强度的材料参数的新信息。一个特殊的目标是研究杂质态中居群反转的条件和起源，并阐明这些机制在调制掺杂Si和SiGe结构中。这项研究可能产生的技术后果是，随着器件尺寸的缩小，指导掺杂剂的选择，并确定基于掺杂剂辐射跃迁的新器件家族的现象。该项目将与Ioffe物理技术研究所（圣彼得堡）和无线电工程和电子研究所（莫斯科）的俄罗斯科学家合作进行。组建的团队具有互补的专业知识和设施来进行拟议的研究。该奖项将为学生、初级和高级研究人员在国际合作中提供教育和发现的机会。特拉华大学和俄罗斯科学家之间的这项合作研究可以更好地理解掺杂SiGe纳米结构的合成和性质，以及确定载流子输运和辐射跃迁的机制。对学生进行技术重要材料项目的教育和培训是拟议的国际合作的一个关键方面。此外，这个项目的成果将被纳入特拉华大学的课程，研究的亮点将在一个网页上展示，旨在向学生和公众提供纳米结构的教育信息。