半导体纳米线阵列的制备和转移及光伏特性研究

Semiconductor nanowires are attractive for potential applications in optoelectronics including photovoltaics in which they could bring distinct advantages such as light trapping and efficient carrier collection. This project aims at investigating the fabrication, characterization and further application in devices of semiconductor nanowire arrays. In the first part of this project, a low-cost, high-throughput and controlled method by combining nanosphere lithography and reactive ion etching will be used to fabricate aligned silicon nanowire arrays with uniform coverage. Moreover, the same method will be applied on materials with superior carrier mobility and direct bandgap as gallium arsenide (GaAs), in order to form GaAs nanowire arrays. The fabricated semiconductor nanowires will be then massively transferred onto another flexible substrate by using a peer-off method, which exhibits the promising potential for the integration of nanowires on versatile substrate. In the second part of this project, a field effect transistor device based on single semiconductor nanowire will be fabricated to investigate the electrical transport properties of such nanowire. The influence of the morphology, array structure and doping level of semiconductor nanowires on their optical and electrical properties will be intensively studied. In the third part of this project, the radial p-n junction will be formed on semiconductor nanowires, which provides short collection lengths for excited carrers in a direction normal to the light absorption. Based on such structure, silicon and GaAs n-p core-shell nanowire solar cells will be finally assembled and their photovoltaic charateristics will be optimized. Such prototype opens a route to the next generation nanostructured solar cell with higher power conversion efficency.

半导体纳米线结构凭借其独特的光吸收特性和电输运性能，在新型太阳电池中具有很大的潜在应用价值。本项目计划开展对半导体纳米线从阵列制备、性能表征到器件应用的系统研究。结合自下而上的纳米球自组装和自上而下的物理刻蚀技术，发展针对硅纳米线阵列的低成本、宏量和可控的制备方法；并且拓展该方法的兼容性，制备光电性能更为优异的砷化镓纳米线阵列。提出纳米线阵列在不同基底上的逐层剥离和大面积转移的方法，将纳米线阵列与柔性基底相结合以实现对其低成本的应用。发展针对单根半导体纳米线的表征技术，揭示纳米线的表面形貌、阵列结构和掺杂浓度等因素对其光学和电学性能的影响规律。研究基于纳米线的径向P-N结，实现在充分吸收太阳光的同时光生载流子的快速分离和输运。最后，构筑一个基于半导体纳米线阵列的光伏器件原型，为新一代基于纳米材料的低成本高效率的太阳电池器件的开发和应用做好基础探索。

在众多类型的纳米材料中，半导体纳米线凭借其一维的柱形结构、独特的电学和光学性能在近年来得到了广泛的关注和深入的研究，特别是在太阳电池应用领域具有很大的潜在应用价值。本项目主要开展对半导体纳米线从阵列制备、性能表征到光伏器件应用的系统研究。在本项目的支持下，我们发展了针对半导体纳米线阵列的宏量及可控制备方法，包括对硅纳米线阵列的纳米球刻蚀技术和对尺寸及分布可控的砷化镓纳米线阵列的自平衡生长；系统研究了纳米线阵列的吸光特性，通过低温扫描隧道显微镜和密度泛函理论计算，在实验上和理论上系统考察了半导体纳米线尤其是异质结构的砷化镓纳米线的表面原子尺度结构和能带结构，并实现了对其电学特性的有效调控；实现具有径向p-n结并能够和零维量子点相结合的新型纳米线复合结构的制备,通过表面钝化等手段优化基于硅纳米线阵列光伏器件的效率。通过本项目的研究，为新一代基于纳米材料的低成本高效率的太阳电池器件的应用做好基础探索。三年期间共发表SCI论文10篇，EI论文2篇，其中包括2篇一区论文和5篇二区论文，以及相关专利1项；培养研究生4名。