可拉伸晶硅网格的引导生长及其在应变条件下的电输运和光吸收特性研究

Crystalline bulk silicon (Si) has been the most mature and reliable semiconductor, but fails to serve the emerging needs of soft and stretchable electronics. How to endow large stretchability to the rigid and brittle c-Si, by means of elastic morphology engineering, is now becoming a hot topic in research. In this project, we propose to explore a novel line-shape engineering mechanism and technology of c-Si nanowires (SiNWs), based on a new in-plane guided growth strategy that we proposed recently, to accomplish stretchable c-Si network and investigate its unique electric transport and optical absorption properties under large stretching strain. Specifically, we will first focus on the growth dynamics of leading metal catalyst droplets, during their guided movement along step edges programmed with high positive or negative curvature, and then assemble them into a continuous and highly stretchable c-Si network; Then, the electric transport and optical absorption properties of the programmable c-Si network will be explored, under different stress/strain conditions, and engineered by means different SiNW line-shape design, network array configuration and electrode contacts; In addition, the experimental results and observations will be analyzed and modeled by multi-field finite element simulation, aiming at extracting and understanding the key mechanical, electric and optical coupling parameters and mechanism, and to optimize the network design. Thus, the goal of this project is to establish a new stretchable c-Si network technology and architecture, which will serve as the very basis for developing a new generation of c-Si based stretchable logic, bio-sensor and flexible display applications.

晶体硅是最为成熟可靠的半导体材料，却难以适应柔性和可拉伸电子的应用需求。如何通过弹性形貌设计实现可拉伸的晶硅材料是近期研究的一大热点。本项目基于我们提出的一种新型的平面纳米线自组装生长模式，研究其在高曲率引导台阶上的引导生长机理与技术，制备形貌可编程调控的可拉伸晶硅纳米线网格，进而研究其在应力作用下的电输运和光吸收特性。具体包括：1）研究纳米金属催化液滴在正、负高曲率引导边界上独特的生长动力学过程，建立可靠的形貌调控手段，及可拉伸晶硅网格的宏量制备技术； 2）探索纳米线网格结构材料在不同的结构参数、沟道形貌和外场应力作用下的应力分布、电输运和光吸收等响应特性。3）结合有限元多场耦合建模分析，针对可拉伸电子和探测应用的不同功能需求，对晶硅网格进行设计优化和验证。研究目标在于，建立一种新型的可拉伸晶硅网格技术和基础框架，为开发新一代硅基可拉伸电子、生物探测和柔性显示等打下关键的理论和实验基础.

晶体硅是最为成熟可靠的半导体材料，却难以适应柔性可拉伸电子应用。通过弹性形貌设计实现可拉伸晶硅成为近期研究热点之一。本项目基于自主创新平面固液固（IPSLS）纳米线生长策略，探索其在高曲率引导台阶上的稳定生长机理，制备形貌可编程的柔性晶硅纳米线网格，系统研究其力学稳定性和电输运及光吸收特性，以期建立一种基础共性的可拉伸晶硅网格Wafer技术，服务于开发新一代高性能、高可靠性的硅基柔性电子应用。项目于2019年启动至2022年底结束历时4年，各项研究任务顺利开展，并按期达成各项预期科研任务指标。具体而言，在项目执行期间，深入探索了IPSLS纳米线的生长形貌调控机理，及其在各种平面及三维高曲率台阶引导下的生长动态，发展了一系列关键的形貌控制、掺杂调控、超低温生长及网格组装技术。结合理论模拟和优化设计，制备出可精准定制的超可拉伸、准连续晶硅纳米线网格；制备了具有优良导电特性且可集成硅镍（NiSi）合金纳米线结构；利用纳米线阵列网格作为精细模板实现批量制备新颖的可拉伸2D网格；提出和实现了纳米线网格空间螺旋堆叠实现高效手性光调制的新技术方案；基于纳米线网格技术展示了高性能可拉伸TFT显示驱动和气氛传感器件，并启动多项重大产学研联合研发专项和实现多项专利成果转化。总而言之，此项目的开展为深入理解纳米线生长调控机理，挖掘弹性形貌设计潜力，开发新一代高性能硅基可拉伸电子、生物探测和柔性显示奠定了关键的理论和实验基础，更为后续规模化产业合作提供了十分有利的条件。在项目执行期间申请人以通讯作者发表SCI论文33篇，其中包括国际一流高水平论文：Nano Letters 5篇，ACS Nano 1篇，Adv Mater. 1篇，Adv Func Mater. 1篇，Small 2篇，Adv. Sci. 1篇及其它IF>10的5篇。申请发明专利34项，获授权发明17项。项目期间培养毕业博士8人和硕士10人，本科生12人，指导在读博士研究生13人，硕士生6人。