多场耦合诱导的二氧化钒纳米线Mott相变及器件研究

Mott insulator vanadium dioxide (VO2) as a typical strongly correlated electron material has attracted intense interest. In this project, we will synthesize the VO2 nanobeams through catalyst-assisted physical vapor deposition process, and assemble one nanobeam into a functional device, where can load different physical fields on at the same time. By coupling the multi-physical field effects of stress, temperature and laser, we try to induce the fast and tunable metal-insulator transition of VO2 nanobeam, and explore the potential coupling law. Based on these results, we will establish the corresponding ternary phase diagram and build a reasonable physical models, which is helpful for a deeper understanding of metal-insulator phase transition mechanism. Furthermore, by adjusting the VO2 nanobeam approaches to the critical point of phase transition, we can develop a high-performance sensitive components based on the metal-insulator transition with variety of response modes. This project can enlighten a new way of thinking for development and application of VO2-based micro- and nanodevices (such as high-speed optical control switches, memory, logic gates, etc.), and has important scientific guiding significance for its application in sensor networks.

我们以典型的强关联Mott绝缘体二氧化钒（VO2）为研究对象，以催化剂辅助生长的单晶纳米线形态为载体，通过设计合理的器件实现在单根VO2纳米线上可以同时加载温度、应力、激光这三种不同的物理场，利用三者的耦合效应来调控纳米线发生快速的金属-绝缘相变，并探索潜在的耦合规律，建立相应的三元相图以及物理模型，使研究者对VO2的金属-绝缘相变机制具有更为深入的理解。并合理利用这种特殊的相变行为，控制纳米线逼近相变临界点，来开发集成多种物理场响应模式的高性能VO2纳米线敏感元件。这为基于VO2及其它强关联电子材料微纳功能器件的开发与应用（如高速光控开关，存储器、逻辑门等）提供了新的思路，对于其在传感网络的应用具有重要的科学指导意义。

项目主要包含两部分：1. 为了利用二氧化钒（VO2）的金属-绝缘相变并用于开发高性能纳微敏感器件，项目实现了高质量VO2纳米线在柔性衬底上的生长并理解了原理，设计基于单根纳米线的器件，通过调控加载在纳米线上的温度、应力、激光来探索耦合物理场的规律。研究原位观测到悬臂纳米线热传导中的两相共存结构及畴壁快速迁移。设计的核壳悬臂VO2纳米线结构由于无应力及低热传递使纳米线相变驱动电压降低了1个数量级的，对于低能耗的相变器件开发提供了一种有效途径。此外，通过局域表面等离子体光热效应实现了相变温度的调制。2. 透明柔性电极是新型柔性光电器件的发展的重要基石之一，项目探索了低成本液相法制作的金属纳米线网络在透明柔性电极上的应用。项目在高长径比的金属纳米线的合成、逾渗模型、排布技术、低温后处理等方面进行了探究，保持低方块电阻的同时提高透过率，获得了90%方阻、10欧姆/□的透明柔性电极，这个性能优于目前采用的商用材料，并且可用简单廉价的液相印刷方式加工，研究已经成功将其用于透明触摸感知界面，柔性太阳能电池，柔性显示，柔性射频标签等多种器件，为这些新兴领域的发展提供了保证。