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

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反应和化学物质的传输。使用这些微球作为纳米线生长基底--“Geode工艺”--有望成为一种新的平台，用于可规模化制造用于一系列应用的功能性半导体纳米线（例如，热电、光学涂层、大面积电子等）。 在Geode工艺中，中空微球为纳米线生长提供了有效的气体传输和大的内表面积，同时防止团聚并保护精细的液滴，从而编排纳米线生长。拟议的研究的总体目标是获得基本的动力学和传输现象的理解，使纳米线合成的精确控制。格鲁吉亚理工学院和ALD纳米解决方案公司的研究人员之间拟议的合作，具有产生变革性结果的潜力，并使该技术的未来商业开发成为可能。工作的具体目标有三个方面：（1）研究稳态实验中的生长速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）进行瞬态实验，重点是当调制前体气体混合物时，纳米线中掺杂剂浓度分布的详细量化;以及（3）初步量化中试规模流化床反应器中的传输性质，以弥合实验室规模合成与可放大反应器技术之间的差距。 除了培训研究生外，研究团队还计划通过Nanovation播客参与社会和教育推广，包括在本科课程中加入与纳米材料相关的材料，并开发一种新的动手流化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流化床反应器技术的潜力，特别是先进的材料和设备processing.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.