Catalyzed Nucleation and Growth of Semiconductor Nanowires

技术。该项目研究半导体纳米线（NWs）的局部催化成核和生长；该方法将模拟和建模与原位和非原位实验相结合。计算和实验方法的紧密结合将有助于对西北向构造演化的机制及其如何被控制的基本理解。将对NW成核和生长动力学进行原子模拟和控制实验，以便进行直接比较。本文将讨论以下与金属催化NW合成有关的问题：NW在不同底物上成核的机制是什么？它与某些催化剂-NW体系中观察到的深亚共晶成核有何关系？Q2。什么机制控制正常的NW生长并导致生长异常（例如扭结）？第三季。NW生长（催化剂纳米颗粒凝固）终止的机理是什么？以Si/Ge NW体系为试验平台，在控制温度和压力条件下CVD生长过程中的原位和非原位测量将与数值预测进行比较，验证和指导计算方法的发展，以克服成核事件建模中的时间尺度挑战。后者是迄今为止原子模拟适用范围的一个众所周知的主要限制。由于在物理、化学和生物过程中经常发生成核事件，因此所获得的新认识有望使原子建模的更广泛领域受益。本项目涉及电子/光子材料科学中具有技术相关性的主题领域的基础研究问题。这项基础研究是在全球学术和工业实验室努力在新设备中使用半导体NWs的背景下进行的，预计将产生强大的技术影响。通过该项目获得的NW合成结果可能对这些和其他新兴技术的发展产生影响。半导体NWs带来的新科学技术突破的前景吸引了本科生、研究生和教师对这类研究的浓厚兴趣。pi计划利用这种“兴奋”，并以此为基础开展教育和推广活动。具体举措将在以下方面进行：1)通过与一名高中科学教师合作，向代表性不足的少数民族开展科学教育；2)在拟进行的研究中具有计算和实验方面的本科经验；3)基于研究成果的本科和研究生课程模块开发。

Technical. This project addresses locally catalyzed nucleation and growth of semiconductor nanowires (NWs); the approach combines simulation and modeling with in situ and ex situ ex-periments. The closely coupled computational and experimental approach should help to gain fundamental understanding of mechanisms of NW structure evolution and how they can be con-trolled. Atomistic modeling and controlled experiments on NW nucleation and growth kinetics will be carried out so as to provide direct comparisons. The following questions related to metal-catalyzed NW synthesis will be addressed: Q1. What is the mechanism of NW nucleation on dif-ferent substrates and how does it relate to the observed deep sub-eutectic nucleation reported in some catalyst-NW systems? Q2. What mechanisms control normal NW growth and result in growth abnormalities (e.g. kinking)? Q3. What is the mechanism of the termination of NW growth (catalyst nanoparticle solidification)? Using the Si/Ge NW system as a test bed, in situ and ex situ measurements during CVD growth at controlled temperature and pressure conditions will be compared with numerical predictions, validating and guiding the development of compu-tational methods to overcome time scale challenges in the modeling of nucleation events. The latter is a well known major limit to the range of applicability of atomistic simulations to date. The new understanding gained is expected to benefit the broader field of atomistic modeling due to the common occurrence of nucleation events in physical, chemical and biological processes.Non-Technical. The project addresses fundamental research issues in a topical area of elec-tronic/photonic materials science having technological relevance. This basic research, being con-ducted within the context of worldwide efforts among academic and industrial labs to use semi-conductor NWs in new devices, is expected to have strong technological impact. Results ob-tained through this project on NW synthesis may have impact on the development of these and other emerging technologies. The prospect of new science and technology breakthroughs enabled by semiconductor NWs attracts strong interest in such research among undergrads, graduate stu-dents, and faculty. The PIs plan to leverage this 'excitement' and build on it in their education and outreach activities. Specific initiatives will be pursued in: 1) science education outreach to under-represented minorities through a collaboration with a high school science teacher; 2) un-dergraduate experiences in both computational and experimental components of the proposed re-search; and 3) undergraduate and graduate course module development based on research find-ings.