Collaborative Research: Identifying and Controlling Conductivity Variations in Semiconductor Nanowires

1604931/1603904 PI：单，曾傑瑞W./Filler，Michael A.标题：合作研究：识别和控制半导体纳米线中的电导率变化半导体纳米线正在成为重要的纳米级构建块，应用范围广泛，包括能量收集、固态照明、热传递、信息处理、化学检测，甚至生物电子。这些纳米材料在结构和组成上表现出显著的差异，这可能会限制它们的功能和性能。更好地理解和控制半导体纳米线合成中的逐次变化将能够精确地调整纳米线的性质，以产生导电性分布比目前最先进的水平窄得多的系综。该项目的重点是对半导体纳米线电导率的变化进行统计评估，了解变化的根本原因，并开发将这种变化降至最低的方法，以便能够进行商业应用。该研究项目涉及将新颖的高通量电取向光谱(EOS)与最先进的纳米线合成技术相结合。EOS是基于交流电场作用下液体悬浮纳米线的频率相关取向速率，每天可以测量大约1000根纳米线的电导率，比现有的直接接触方法快数百倍。通过对纳米线生长的基本化学理解，可以仔细控制影响掺杂剂掺入的异质界面过程。初步数据证实，纳米线的导电性在一个整体内可以有很大的变化。拟议的工作将侧重于确定影响半导体纳米线电导率的关键工艺参数，并开发减少电导率变化的新工艺。将研究两类纳米线：(1)不同n和p性质的均匀掺杂的Si和Ge纳米线；(2)SiGe合金、核壳和其他非均相纳米线。虽然硅和锗纳米线是该项目的重点，但该方法预计将适用于其他材料的广泛范围(例如，III-V半导体、氧化物等)。该项目将涉及对研究生的跨学科和跨大学培训，招募少数族裔本科生到主要研究人员的实验室进行研究项目，课程开发活动，以及旨在吸引K-12学生从事STEM职业的外联努力。

1604931 / 1603904 PIs: Shan, Jerry W. / Filler, Michael A. Title: Collaborative Research: Identifying and Controlling Conductivity Variations in Semiconductor NanowiresSemiconductor nanowires are emerging as important nanoscale building blocks for applications as diverse as energy harvesting, solid-state lighting, heat transfer, information processing, chemical detection, and even bioelectronics. These nanoscale materials exhibit significant variations in their structure and composition that can limit their function and properties. A better understanding and control of run-to-run variations in semiconductor nanowire synthesis will enable precise tuning of nanowire properties to yield ensembles with conductivity distributions far narrower than the current state-of-the-art. This project focuses on statistically assessing variations in the electrical conductivity of semiconductor nanowires, understanding the underlying causes for the variations, and developing methodologies that minimize the, in order to enable commercial applications. The research project involves coupling novel high-throughput electro-orientation spectroscopy (EOS) with state-of-the-art nanowire synthesis techniques. EOS is based on the frequency-dependent alignment rates of liquid-suspended nanowires subjected to an AC electric field and can measure the conductivity of about one thousand nanowires per day, hundreds of times faster than existing direct-contact approaches. A fundamental chemical understanding of nanowire growth allows for careful control of the hetero-interfacial processes that influence dopant incorporation. Preliminary data confirm that nanowire conductivity can vary considerably within an ensemble. The proposed work will focus on identifying the critical process parameters that affect electrical conductivity in semiconductor nanowires and on the development of new processes that reduce conductivity variations. Two classes of nanowires will be studied: (1) uniformly-doped Si and Ge nanowires of varying n and p character and (2) SiGe alloy, core-shell, and other heterogeneous nanowires. While Si and Ge nanowires are the focus of this project, the approach is expected to be applicable to a broad spectrum of other materials (e.g., III-V semiconductors, oxides, etc.). The project will involve cross-disciplinary and cross-university training of graduate students, recruiting of minority undergraduate students into pursuing research projects in the laboratories of the principal investigators, curriculum development activities, and an outreach effort aiming at engaging K-12 students into pursuing STEM careers.