Fabrication and Optimization of Highly Ordered Assemblies of Metallic Nanowire and Nanoparticle Arrays

美国国家科学基金会-化学和运输系统分部颗粒和多相过程项目（1415）提案编号：0731349主要研究人员：Ragan， Regina隶属关系：加州大学欧文分校提案标题：在硅衬底上的金属/稀土二硅化物核壳纳米结构阵列具有高密度和均匀的尺寸和形状，将被设计、建模和表征，以纳入生物传感器系统。虽然贵金属纳米结构在生物传感器的单分子检测限制方面表现出了非凡的能力，但利用其独特性能的技术发展面临的最重大挑战之一是使用低成本和高通量技术制造具有单分散尺寸，形状和高密度的阵列。最近，首席研究员开发了一种独特的超大规模兼容制造工艺，用于在Si衬底上致密（~1011 cm-2）有序排列单分散Pt和Au核壳纳米结构。Pt和Au原子在自组装纳米线模板上进行物理气相沉积，然后进行反应离子刻蚀，得到的贵金属/稀土二硅化物核壳纳米结构阵列平均粒径小于10 nm，尺寸分布较窄，为1 nm，颗粒间距为~ 10 nm，无需光刻。制备：初步结果表明，所提出的合成路线在Si（001）衬底上自组装的稀土二硅化物纳米线上产生了Pt和Au纳米结构。因此，这种成功的制造技术将被应用于制造银和其他金属核壳结构，以调谐不同频率范围内的光学响应。理论：理论计算自组装模板的表面原子结构，它们与Si（001）表面的界面，以及贵金属原子在纳米线模板表面上的聚集。我们的目标是了解组装机制，以优化结构，使我们的过程可翻译到其他材料系统。表征：表面结构和电子态的原子级分辨率将通过STM和光谱学进行研究。智力优势：直径远小于光波长的金属纳米结构和较窄的粒子间间距具有很强的近场耦合，因为这些粒子周围的电磁场局部增强。我们将在此背景下解决基本问题：1)阵列中纳米结构的排列如何影响信号增强；2)如何有效地在大表面上绘制纳米结构的图案。采用微电子加工方法，结合自组装和光刻技术，在硅衬底上制备阵列格式的单分散金属纳米结构是本方案的独特之处。通过自组装工艺，可获得的特征尺寸为8 nm，颗粒间距为~10 nm，比电子束光刻获得的特征尺寸要小，吞吐量要高得多；因此可以获得独特的光学性质。协同的理论和实验研究将允许有效和合理的优化，并最终大规模生产用于生物传感器的纳米结构。更广泛的影响：纳米结构阵列的创新和高通量制造技术对许多新兴技术，如纳米催化、自旋电子学、量子计算和光化学具有重要意义。这项基础研究将为成功制造高密度、均匀分散、优化生物传感器应用的纳米结构阵列铺平道路。我们提出的制造技术显然可用于其他应用，并且由于与当前半导体制造技术的兼容性，可以扩展到大规模生产的大面积。该提案还将通过研究机会和外展活动支持对高中生、本科生和研究生的持续培训。

National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0731349 Principal Investigators: Ragan, Regina Affiliation: University of California Irvine Proposal Title: Fabrication and Optimization of Highly Ordered Assemblies of Metallic Nanowire and Nanoparticle Arrays Metal/rare earth disilicide core-shell nanostructure arrays on silicon substrates that have high density in addition to uniform size and shape will be designed, modeled, and characterized for incorporation into biosensor systems. Although noble metal nanostructures have demonstrated extraordinary capacity for single molecule detection limits in biosensors, one of the most significant challenges to technological developments that capitalize on their unique properties is the fabrication of arrays with monodisperse size, shape and high density using a low cost and high throughput technique. Recently, the principal investigator has developed a unique ultralarge scale compatible fabrication process for dense (~1011 cm-2) ordered arrays of monodisperse Pt and Au coreshell nanostructures on Si substrates. Physical vapor deposition of Pt and Au atoms on self-assembled nanowire templates followed by reactive ion etching produces noble metal/rare earth disilicide core-shell nanostructure arrays with mean particle diameter of less than 10 nm, a narrow size distribution, 1 nm, and inter-particle spacing of ~ 10 nm without lithography. . Fabrication: Preliminary results demonstrate that the proposed synthesis route produced both Pt and Au nanostructures on self-assembled rare earth disilicide nanowires on Si(001) substrates. This successful fabrication technique will thus be applied to fabricate Ag and other metal core-shell structures in order to tune optical responses in different frequency range. . Theory: Theoretical calculations of surface atomic structures of self-assembled templates, their interfaces with the Si(001) surface, and noble metal atom aggregation on nanowire template surfaces will be performed. The goal is to understand assembly mechanisms in order to optimize structure and make our process translatable to other material systems.. Characterization: Atomic level resolution of surface structures and electronic states will be investigated by STM and spectroscopy. Intellectual Merit: Metal nanostructures with diameters much less than the wavelength of light and narrow interparticle spacing have strong near field coupling due to a local enhancement of the electromagnetic field around these particles. We will address fundamental questions in this context: 1) how the arrangement of nanostructures in arrays affects signal enhancements; and 2) how to effectively pattern nanostructures over a large surface. Fabrication of monodisperse metal nanostructures in array format on Si substrates using microelectronic processing methods and combining self- assembly with lithography is unique to this proposal. Through the self-assembly process, the feature size, 8 nm, and inter-particle spacing achievable, ~10 nm, are smaller than that obtained with electron beam lithography and the throughput is much higher; thus unique optical properties can be attained. The synergistic theoretical and experimental studies will allow efficient and rational optimization and eventually massive production of nanostructures for biosensor applications.Broader Impact: Innovative and high-throughput fabrication techniques of nanostructure arrays are significant for many emerging technologies such as nanocatalysis, spintronics, quantum computing and optochemistry. This proposed fundamental study will pave the way for successful fabrication of high density, uniformly dispersed, nanostructure arrays optimized for biosensor applications. Our proposed fabrication technique is apparently translatable for other applications and affords the possibility to scale to large areas for massive production due the compatibility with current semiconductor manufacturing technology. This proposal will also support the continued training of high school, undergraduate and graduate students through research opportunities and outreach activities.