ZnO-MgZnO多量子阱纳米线阵列/金属局域表面等离激元复合体系的制备、物性调控及其紫外LED研究

UV light-emitting materials and devices, a subject of intense research in optoelectronic information field, possess a wide range of applications in solid-state lighting, information storage, environment protection and life science. This proposal aims to increase the luminescence efficiency of ZnO-based UV LEDs by introducing a composite material system, which consists of ZnO-MgZnO multi-quantum-wells nanowire array (MNA) and metal localized surface plasmons (LSPs), as active layer into light-emitting devices. The ZnO-MgZnO MNA will be prepared via pulsed laser deposition technology and their structural and optoelectronic properties will be studied in detail by various characterization methods; based on FDTD simulation, metal (e.g. Ag and Pt) nanoparticles will be incorporated into the MNA and forming ZnO-MgZnO MNA/metal LSPs composite system; the effect of resonant coupling between ZnO exciton and metal LSP on the internal and external quantum efficiency of luminescence would be detailedly investigated and the enhancement mechanism of UV emission from this composite system will also be uncovered; UV LEDs will be constructed by introducing the above composite system as active layer; relevant carrier dynamic process (e.g. injection, transportation, recombination and relaxation) in the devices will be studied and the correlation between device performance and composite system structure shall also be established. This project will not only provide an effective way to improve the ZnO-based UV LED efficiency, but also be helpful for the design and fabrication of high-efficiency light-emitting devices based on other luminescent materials.

紫外LED在照明、信息、环保和生命等领域有广阔的应用前景，是当前光电子信息领域中极为重要的研究方向。本课题针对ZnO基紫外LED效率较低的困难，拟开展ZnO-MgZnO多量子阱纳米线阵列(MNA)/金属局域表面等离激元(LSP)复合体系的制备、物性调控及其紫外LED的研究工作。采用PLD技术制备ZnO-MgZnO MNA，并确定其光电性质与结构参数的相关性；基于FDTD模拟，利用物理沉积或湿化学方法将Ag、Pt等金属粒子引入到上述MNA中，形成ZnO-MgZnO MNA/金属LSP复合体系，探究ZnO激子与金属LSP耦合的内在机制以及对光发射效率的影响，揭示该复合体系紫外发光增强的机理；以上述复合体系为有源层构建LED，研究器件中载流子的注入、输运、复合、弛豫等动力学过程，揭示器件性能与复合体系结构的相关性，实现提升ZnO基紫外LED效率的最终目标，并为其它发光器件的效率改善提供参考方案。

宽禁带半导体ZnO因具有高达60 meV的激子束缚能，较高的光学增益系数，是发展紫外光发射器件的理想材料之一。本项目聚焦ZnO基材料在高效紫外光电子器件领域内的应用需求，从结构设计、材料生长、物性调控、器件制备、性能优化等几个方面，分阶段系统地研究了基于ZnO材料的紫外光发射器件，取得的主要创新性成果如下：. 1）利用局域表面等离激元（LSP）与ZnO激子/光子之间的共振耦合效应，有效地提高了有源层的内量子效率和光萃取效率，实现了对p-GaN/i-ZnO/n-ZnO和Au/MgO/ZnO MIS型薄膜异质结近7倍的紫外电致发射增强。2）进一步，利用量子点（QDs）具有量子限域效应和高发光效率的优势，通过室温溶液法制备了尺寸均一、结晶性好的ZnO量子点，并以其为有源层，构建了p-GaN/ZnO QDs/Al2O3/ZnO QDs量子点LED（QLED）。在这一设计中，我们首次提出利用超薄非晶Al2O3层对电子的散射和阻滞作用，平衡了有源区内电子、空穴的注入效率，显著地增强了该ZnO基QLED的电致发光强度。3）此外，引入新型碳基LSP与ZnO QDs进行耦合，制备出了首个碳基LSP修饰的ZnO紫外发光器件。利用碳基LSP低光学损耗和宽带可调的共振特性，将该ZnO基QLED电致发光强度显著提升了近20倍。. 本项目研究结果对于理解宽禁带半导体材料及其光电器件物理具有一定的参考价值，并为研发基于其它宽禁带半导体材料的光电器件提供科学依据和技术参考。