基于高阶多极子共振模式的等离子体增强型ZnO基紫外探测器的研究

ZnO-based semiconductor has been considered as one of the most ideal materials for the application as UV photodetectors due to its low defect density, ultra-high radiation hardness, and high saturated carrier drift velocity. However, the relative technology of ZnO-based materials is not mature. In particular, the high quality p-type doping is still a big challenge. Thus, most devices are based on metal-semiconductor-metal structures, and their performance is usually very poor. Although metal surface plasmonic has been widely used to improve the performance of optoelectronic devices, the efficient enhancement is still difficult to be realized in the UV range for the traditional plasmon-enhanced photodetectors. The reason is that the traditional enhancements are usually based on dipole plasmon resonances, whose peaks are mostly in the visible and IR range and are relatively broad. In this project, we will use the quadrupole plasmon resonance in Ag nanoparticles to solve the above problem.The important advantage of this idea is that the narrow Ag quadrupole resonance peak locates at UV range, and thus can realize an efficient performance enhancement of ZnO-based UV photodetectors with highly wavelength selectivity. Therefore, the method in this project help to solve the problem of inefficient performance enhancement of UV photodetectors by traditional dipole plasmon resonance, and it is expected to realize plasmon-enhanced ZnO-based UV photodetectors with high performance.

ZnO基半导体具有缺陷密度低，抗辐射性强以及饱和载流子漂移速率高等特性，并可通过Mg的掺杂使得带隙大范围连续可调，因此被认为是制作紫外探测器的最理想材料之一。但是，ZnO基材料相关工艺发展不成熟，特别是高质量的p型掺杂还是个国际难题，这使得现有器件以金属-半导体-金属结构为主，且性能普遍不高。尽管金属表面等离子体被广泛的用来提高光电器件的性能，但是，传统的等离子体增强型探测器通常利用偶极子共振模式，由于偶极子共振峰通常位于可见和红外波段，且共振峰频谱宽，很难在紫外波段实现高效的选择性增强。针对该难题，本项目中我们利用Ag等离子体的四极子共振模式位于紫外波段并且共振峰频谱窄的特性，实现ZnO基材料对紫外波段探测能力的选择性增强。因此，该方法有助于解决传统器件中等离子体偶极子共振模式不能有效增强紫外波段探测能力的问题，从而有望实现高性能的等离子体增强型ZnO基紫外探测器。

紫外探测技术是继红外和激光探测技术之后发展起来的又一军民两用的光电探测技术，它在军事，科研，工农业生产以及日常生活方面发挥了越来越大的作用。ZnO基宽禁带半导体是理想的紫外探测材料，但由于缺乏高效稳定的p型材料，因此已报道的大部分器件都采用简单的金属-半导体-金属结构,但是它们的性能通常低于人们的预期。金属表面等离子体效应是提高光电器件性能的一个典型而重要的方法，但大的能量失配使得利用传统偶极子共振很难在紫外波段实现高效的增强效果。针对上述难题，本项目提出利用Ag纳米粒子团簇的四极子等离子体来提高ZnMgO金属-半导体-金属结构紫外探测器的性能，探索出增强紫外探测能力的新方法和新机制。本项目从高质量的ZnO基外延薄膜及其紫外探测器件的制备入手，研究生长条件和制备工艺对材料和器件性能的影响，研究银纳米粒子的表面等离子体效应及其对氧化锌基紫外探测器性能的影响，期待实现高性能紫外探测器。本项目实现了首个基于高阶共振的等离子体增强型紫外探测器，利用随机Ag 纳米颗粒的等离子体四极子振荡模式，实现了ZnO薄膜在紫外波段的光谱响应度的显著的、高波长选择性的增强，获得了仅为10纳米的紫外响应谱半峰宽（为已知最窄），拓展了金属粒子在光电器件领域的应用，被国际同行评价为“开启了高阶等离子体在紫外光电器件领域的应用之门”。