基于金-硅肖特基纳米线阵列的光电转换调控与折射率传感研究

The sensing technologies based on surface plasmonics are hot research topics in recent years, due to the benefits of no calibration, real-time, no-contact, no-damage, etc. However, the current devices are usually composed by the complicated structured, with a high fabrication complexity and optically characterized, which will limit the sensing application. In this project, we propose a gold-silicon conformal nanowire array system by deeply exploiting surface plasmonic resonance (SPR) and regulation mechanisms, and we then establish the gold-silicon Schottky junction photoelectric conversion system. By doing this, the sensing performance can be significantly improved and the new refractive index sensing testing method based on photocurrent can be first proposed. Based on the easy fabricated silicon nanowire array, the conformal gold shell is introduced. Through combining light trapping with high sensitivity to the environment of SPR, the narrow-band, wide-angle and efficient optical performance can be realized and the refractive index sensing performance can be largely improved. We further establish a new system on gold-silicon Schottky junction hot-electron photoconversion, and the comprehensive mathematical, physical and simulation models on interior carrier separation process, in order to precisely and rapidly detect the changes in background refractive index by photocurrent testing. Finally, the fabrication, characterization and testing of the proposed devices are performed, in order to explore the stable and simplified fabrication schemes. The successful implementation of this project can promote the understanding of the basic mechanism of hot-electron photoconversion and optical sensing mechanism, as well as contribute the novel designs and fabrications of these devices.

表面等离子共振传感技术具备无需标定、实时、非接触、无损伤等优点，是近年研究热点。然而，相关器件结构复杂、制作成本高、以光学测试为主，使传感应用受到较大限制。本项目通过深入探索金-硅共形纳米线阵列的表面等离子共振和调控机制，构筑金-硅肖特基光电转换系统，在提升器件光学传感性能的同时，提出基于光电流的新型折射率传感测试方法。项目在易于制备的硅纳米线阵列上覆盖共形金层，将纳米线阵列的超强陷光与表面等离子共振对环境的高敏感性有机结合，获得窄带、广角、强吸收光学性能，大幅提高折射率传感性能。进一步地，构建金-硅肖特基结热电子光电转换系统，严格构筑内部载流子分离过程的数学、物理和仿真模型，通过光电流测试来检测背景折射率的变化，提高测试的准确性和快速性。在此基础上，开展器件制备和光电性能测试，探索稳定、易行的制备工艺流程。项目的实施可促进对热电子光电转换和光学传感机制的科学理解，获得新颖的设计制备方案。

表面等离子共振传感器件结构复杂、制作成本高、以光学测试为主，使传感应用受到较大限制。因此，提高传感器件性能系数和开发基于光电流的新型折射率传感测试方法是亟待解决的关键问题。.本项目在易于制备的硅纳米线阵列上覆盖共形金层，首先利用经典光学理论对器件进行电磁场分析，再根据反射光谱响应进行实时结构调控，以获得最佳光谱响应，获得窄带、广角、强吸收光学性能；然后在已获得的最佳光谱响应的基础上，模拟背景折射率变化，研究器件折射率灵敏度（S）和性能系数（FOM）；进一步地，构建金-硅肖特基结热电子光电转换系统，严格构筑内部载流子分离过程的数学、物理和仿真模型，通过光电流测试来检测背景折射率的变化，提高测试的准确性和快速性。研究发现该结构应用于折射率传感具有多项优点：1）S可达1008nm/RIU；2）FOM约为100，峰值半宽为9.89nm；3）肖特基结电学仿真发现在三种典型折射率情况下光电响应度均可达4mA/W，且光响应谱峰值也随着折射率变化发生相应移动。最后，本项目对金-硅共形纳米线阵列的制备与测试展开了系统的实验研究（包括特征尺寸在2μm以上的硅微米线和0.3—2μm之间的硅微纳米线），同时研究了工艺参数与形貌构筑的关系，获得了工艺控制稳定、重复性好、精确度高的目标结构。本项目采用聚苯乙烯（PS）球自组装技术和剥离工艺制备目标结构——金-硅共形纳米线阵列（周期为1000nm，硅纳米线直径为350nm，硅纳米线高度为1.52μm）。通过PS球的原始直径控制微纳结构的周期，通过等离子刻蚀（ICP-RIE）减小PS的直径来控制所需微纳米线直径。该方法可以实现大面积、批量周期性硅纳米线结构的可控制备，并以此为基底借助磁控溅射技术沉积共形金膜。项目的实施为金-硅纳米线阵列传感器件的设计提供了一套仿真模型，为新型传感器件的基础研究和应用开发提供新设计思路；掌握金-硅纳米线阵列制备的关键技术，为该项技术走向应用奠定了一定的实验基础。