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

本研究计划将结合实验和数值模拟方法，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，在我们之前的纳米粒子和纳米线激光连接工作的基础上，建立激光与其他加工参数、半导体纳米线与金属电极/衬底的不同连接的冶金特性、界面结构以及所选纳米线电子元件和器件的电接触特性和性能之间的基本关系。***有三个具体目标，即：(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过程中工艺参数与接头形成的关系；(2)研究激光加工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性能；(3)构建基于纳米线的电子器件原型，探索其电性能与界面结构和电接触特性的关系，研究金属-半导体界面的载流子输运机制。***该计划将涵盖氧化物半导体纳米线，如TiO2， ZnO和CuO，以及金属电极，如Au， Ag和Ti。初始加工参数包括激光影响、脉冲持续时间、光斑大小等。将使用先进的分析设备，如透射电子显微镜和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。电学性质，如欧姆触点的接触电阻和肖特基触点的能量势垒高度将作为界面结构的函数进行研究。将研究功能原型元件和器件的电性能，如场效应晶体管和忆阻器。数值模拟的实例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础见解，而且还将开发纳米级器件激光精密组装的专有技术。在材料科学与工程、激光加工和纳米器件开发等领域培养具有尖端知识和技能的高素质人才（HQP） 13人，其中博士、硕士研究生6人，本科生在职生4人，博士后3人。加拿大未来的竞争力也将通过他们在加拿大学术界、工业界和研究机构的未来地位得到增强。

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.