Reaction/Transport Behavior in the Synthesis of Functionally-Encoded Nanowires via the Geode Process

这项拟议的项目将研究在中空多孔壁微球的内表面上合成半导体纳米线所涉及的化学物质的化学反应和传输。使用这些微球作为纳米线生长衬底--“Geode工艺”--有望成为可扩展制造功能半导体纳米线的新平台，用于一系列应用(例如，热电、光学涂层、大面积电子等)。在Geode工艺中，空心微球为纳米线生长提供了高效的气体传输和较大的内表面积，同时防止了团聚并保护了编排纳米线生长的微妙液滴。拟议研究的首要目标是对潜在的动力学和传输现象有一个基本的了解，以实现对纳米线合成的精确控制。佐治亚理工学院和ALD NanoSolutions公司的研究人员之间拟议的合作，有可能产生变革性的结果，并使这项技术未来能够进行商业开发。将采用一种新的实验方法。这项工作的具体目标有三个方面：(1)研究稳态实验中的增长率作为反应条件的函数，以量化任何质量和热传递限制并优化微球结构，以减轻对纳米线质量的不利影响；(2)进行瞬变实验，重点是详细量化前体气体混合物时纳米线中的掺杂浓度分布；以及(3)初步量化中试规模的流态化反应器中的传输特性，以弥合实验室规模的合成和可扩展的反应器技术之间的差距。除了培训研究生外，研究小组还计划通过NanoVation播客参与社会和教育宣传，将与纳米材料相关的材料纳入他们的本科课程，并开发一种新的动手沸腾床活动，用于课堂使用和K-12推广。这些活动将突出大规模纳米制造和沸腾床反应器技术的潜力，专门用于先进材料和设备处理。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed project will investigate the chemical reactions and transport of chemical species involved in the synthesis of semiconductor nanowires on the interior surface of hollow, porous-walled microspheres. The use of these microspheres as nanowire growth substrates -- the "Geode process" -- promises to be a new platform for the scalable manufacturing of functional semiconductor nanowires for a range of applications (e.g., thermoelectrics, optical coatings, large-area electronics, etc.). In the Geode process, hollow microspheres provide efficient gas transport and a large internal surface area for nanowire growth while preventing agglomeration and protecting the delicate liquid droplet that choreographs nanowire growth. The overarching objective of the proposed research is to gain a fundamental understanding of the underlying kinetics and transport phenomena to enable precise control of nanowire synthesis. The proposed collaboration between researchers from Georgia Tech and ALD NanoSolutions, Inc., has the potential of producing transformative results and enabling future commercial exploitation of this technology.A novel experimental methodology will be employed. The specific objectives of the work are three-fold: (1) study the growth rate in steady state experiments as function of reaction conditions to quantify any mass and heat transfer limitations and optimize microsphere structure to mitigate adverse impacts on nanowire quality; (2) perform transient experiments that focus on detailed quantification of dopant concentration profiles in the nanowires when precursor gas mixtures are modulated; and (3) preliminarily quantify transport properties in a pilot-scale fluidized bed reactor to bridge the gap between lab-scale synthesis and scalable reactor technology. In addition to training graduate students the research team plans to engage in societal and educational outreach via the Nanovation podcast, by including material related to nanomaterials in their undergraduate courses, and by developing a new hands-on fluidized bed activity for classroom use and K-12 outreach. These activities will highlight the potential of large scale nanomanufacturing and fluidized bed reactor technology specifically for advanced materials and device processing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.