Collaborative Research: GOALI: Nanocrystal Formation and Morphology in Nonthermal Plasmas

奖项摘要CTS-0500332主要研究者：Uwe R. Kortshagen机构：明尼苏达大学双城分校提案标题：合作研究：GOALI：非热等离子体中的纳米晶体形成和形态晶体纳米颗粒作为各种新型纳米系统和器件的构建块被深入研究。在纳米颗粒材料中，硅由于其优异的电子特性、其在微电子制造中的广泛应用、其低毒性以及不存在环境危害而发挥重要作用。低压等离子体--在大气压力的一小部分下产生的部分电离气体--提供了几种独特的性质，这些性质对晶体硅纳米颗粒的合成非常有利。等离子体允许基于直接气体到颗粒转化的效率的高处理速率。与其他气相工艺相比，等离子体提供的优点是颗粒带单极负电荷，这强烈抑制或完全避免了纳米颗粒的有害团聚。这个合作研究/GOALI项目的重点是研究等离子体工艺，该工艺被证明可以产生具有高度独特的几乎完美的立方体形状的高质量硅纳米颗粒。颗粒尺寸高度均匀，几乎没有可检测到的晶体缺陷。这种纳米晶体似乎是纳米级器件如新型垂直肖特基势垒晶体管或发光器件的理想构建块。虽然研究将集中在一个特定的等离子体过程中，这些研究将有助于回答更广泛的悬而未决的问题。其中包括晶体颗粒如何在接近室温的等离子体环境中形成，以及为什么硅颗粒会呈现出非常不寻常的立方体形状，这对于器件应用来说是理想的，但对于纯硅颗粒来说不是平衡形状。技术研究的目的是发现等离子体性质与合成粒子性质之间目前未知的关系。该项目的目标有四个：（1）合成过程中等离子体特性的实验表征;（2）粒子特性的实验研究，包括粒子的尺寸分布、结晶度和形态;（3）等离子体特性和粒子引起的等离子体动力学的数值研究;（4）等离子体工艺条件与颗粒结晶度和形貌关系的原子模拟研究。任务（1）-（3）将由明尼苏达大学的小组进行，任务（4）将由马里兰州的小组进行。GOALI的工业合作伙伴是InnovaLight，Inc.，总部位于明尼苏达州圣保罗，该公司致力于开发基于硅纳米晶体的固态光源。NSF-IGERT项目为“纳米粒子科学与工程”提供的杠杆作用将增强该项目的更广泛影响。至少有三名研究生和少数民族本科生的参与将促进研究与培训的结合以及代表性不足群体的参与。与InnovaLight的密切合作将确保快速向行业转移知识。这将促进并加速潜在商业应用的发展，例如更节能的光源以及电子设备和生物医学诊断。 该项目由NSF和美国能源部在NSF/DOE基础等离子体科学和工程合作伙伴关系下共同资助。

Award AbstractCTS-0500332Principal Investigator: Uwe R. KortshagenInstitution: University of Minnesota - Twin Cities Proposal Title: Collaborative Research: GOALI: Nanocrystal Formation and Morphology in Nonthermal PlasmasCrystalline nanoparticles are intensely studied as building blocks for a wide variety of novel nanoscale systems and devices. Among nanoparticle materials silicon plays an important role due to its excellent electronic properties, its wide use in microelectronics manufacturing, its low toxicity, and the absence of environmental hazards. Low-pressure plasmas-partly ionized gases created at only a fraction of the atmospheric pressure-offer several unique properties that are highly beneficial for the synthesis of crystalline silicon nanoparticles. Plasmas allow for high processing rates based on the efficiency of direct gas-to-particle conversion. Compared to other gas phase processes, plasmas offer the advantage that particles are unipolarly negatively charged, which strongly suppresses or completely avoids detrimental agglomeration of nanoparticles. This Collaborative Research/GOALI project focuses on the study of a plasma process that was shown to yield high-quality silicon nanoparticles with highly unique virtually perfect cubic shapes. Particles are highly uniform in size and exhibit virtually no detectable crystal defects. Nanocrystals of this kind appear to be ideal building blocks for nanoscale devices such as novel vertical Schottky barrier transistors or light emitting devices. While the research will focus on a particular plasma process, the studies will help to answer much broader unresolved questions. Among those are how crystalline particles can be formed in a plasma environment that is close to room temperature, and why silicon particles would assume the highly unusual cubic shape, which is ideal for device applications but is not the equilibrium shape for pure silicon particles. The technical studies aim at finding the currently unknown relations between plasma proper-ties and the properties of the synthesized particles. The project pursues four goals: (1) the ex-perimental characterization of the plasma properties in the synthesis process; (2) the experimen-tal study of particle properties including their size distribution, particle crystallinity, and mor-phology; (3) the numerical study of the plasma properties and plasma dynamics caused by the presence of particles; and (4) the atomic simulation study of the relation between the process plasma conditions and the particle crystallinity and morphology. Tasks (1)-(3) will be pursued by the group at the University of Minnesota, task (4) by the group at the University of Maryland. The GOALI industrial partner is InnovaLight, Inc., based in St. Paul, MN, a company that pur-sues the development of solid state light sources based on silicon nanocrystals. The leverage provided by an NSF-IGERT project for "Nanoparticle Science and Engineer-ing" will enhance the broader impact of this project. The involvement of at least three graduate students and minority undergraduate students will foster the integration of research and training and the involvement of underrepresented groups. The close collaboration with InnovaLight will ensure rapid knowledge transfer to industry. This will enable and accelerate the development of potential commercial applications such as more energy-efficient light sources as well as elec-tronic devices and biomedical diagnostics. This project is co-funded by NSF and the U.S. De-partment of Energy under the NSF/DOE Partnership for Basic Plasma Science and Engineering.