Laser joining and assembly of nanowires: processing, structure, properties and performance

这项研究计划将采用实验和数值模拟相结合的方法，研究纳米线激光连接和组装的基础和工程问题。我们的目标是在我们以前关于纳米粒子和纳米线激光连接的工作的基础上，建立激光与其他工艺参数、半导体纳米线与金属电极/衬底不同接头的冶金特性、界面结构以及选定的基于纳米线的电子元件和器件的电接触特性和性能之间的基本关系。具体目标有三个：(1)基于界面区域的定量(或半定量)热历史，研究纳米线激光连接工艺参数与接头形成之间的关系；(2)研究激光工艺参数对界面结构的影响，包括界面处的晶体取向关系和电接触特性；(3)构建基于纳米线的电子器件原型，探索其与界面结构和电接触性能的关系，并研究金属-半导体界面的载流子传输机制。该计划将涵盖氧化物半导体纳米线，如二氧化钛、氧化锌和氧化铜，以及金属电极，如金、银和钛。初始工艺参数将包括激光通量、脉冲宽度、光斑大小等。将使用先进的分析设备，如透射式电子显微镜和X射线光电子发射显微镜，详细研究冶金缺陷和界面上的晶体取向关系等。将研究电性能，如欧姆接触的接触电阻和肖特基接触的能垒高度作为界面结构的函数。将研究场效应晶体管和忆阻器等功能原型元件和器件的电气性能。数值模拟的例子包括热历史的有限元分析和界面结构的分子动力学模拟。该项目的成功实施不仅将提供激光-纳米线相互作用等有价值的基本见解，还将开发激光精密组装纳米设备的技术诀窍。该计划还将培养13名高素质人才(HQP)，其中包括6名博士生和硕士生，4名本科工作期生和3名博士后研究员，他们拥有材料科学与工程、激光加工和纳米器件开发领域的前沿知识和技能。加拿大未来的竞争力也将通过他们未来在加拿大学术界、工业和研究机构的职位而得到增强。

This proposed research program will study both fundamental and engineering issues in laser joining and assembly of nanowires, with combined experimental and numerical modeling methods. The goal is to, based on our previous work on laser joining of nanoparticles and nanowires, establish fundamental relationships between laser and other processing parameters, metallurgical characteristics of dissimilar joints of semiconductor nanowires and metal electrodes/substrates, interfacial structure, and electrical contact properties and performance of selected nanowire based electronic components and devices. There are three specific objectives, i.e., (1) to study relationships between processing parameters and joint formation in laser joining of nanowires, based on quantitative (or semi-quantitative) thermal history at interfacial regions; (2) to investigate the effect of laser processing parameters on interfacial structures, including crystallographic orientation relations at the interface, and electrical contact properties; and (3) to build prototype nanowire based electronic devices and explore their electrical performance as related to interfacial structure and electrical contact properties, and study the carrier transport mechanisms at the metal-semiconductor interfaces. The program will cover oxide semiconductor nanowires, such as TiO2, ZnO and CuO, and metal electrodes such as Au, Ag and Ti. Initial processing parameters will include laser fluences, pulse duration, spot size, etc. Advanced analytical equipment such as transmission electron microscopy and X-ray photoelectron emission microscopy will be used for detailed study of metallurgical defects and crystal orientation relations at interfaces, etc. Electrical properties such as contact resistance of Ohmic contacts and energy barrier height of Schottky contacts will be studied as functions of interfacial structures. Electrical performance of functional prototype components and devices such as field effect transistor and memristor will be investigated. The examples of numerical modeling include finite element analysis of thermal history and molecular dynamic simulation of interfacial structures. The successful execution of this program will not only provide valuable fundamental insights such as laser-nanowire interactions, but also develop know-how technologies in laser precision assembly of nanoscale devices. This program will also train 13 highly qualified personnel (HQP), including six doctoral and master's students, four undergraduate work-term students and three post-doctoral fellows with cutting edge knowledge and skills in the fields of materials science and engineering, laser processing and nanoscale device development. Canada's future competitiveness will also be enhanced through their future positions in Canadian academia, industries and research institutes.