基于一维纳米材料/量子阱复合结构的氧化锌紫外发光二极管研究

The potential applications of ultraviolet (UV) light-emitting diodes (LEDs) can be expected in the domains of optical communication, solar-blind detection, high-density storage, biomedicine and so on. However, there are still many issues with low luminescent efficiency and intensity, high cost, etc. In this project, the ZnO semiconductor will be used as the UV luminescent materials for its wide and direct bandgap, and high exciton binding energy. The nanomaterials with small-size effect and surface effect, the quantum well (QW) with quantum confinement effect, will be combined in the LEDs to reduce the lattice mismatch and polarization effect in QWs, increase the QW active area and improve the light extraction efficiency. Through the execution of this project, obtaining high quantum efficiency and good monochromaticity of the ZnO-based one-dimensioned nanomaterials/QW UV LEDs can be expected by optimizing energy band structure, electrical properties, crystalline nature, and referencing the result of device simulation. By studying the photoelectric properties of the UV LEDs, the origins of the light emission and the mechanism of wavelength control will be clarified, the processes of carrier transport and radiative recombination in one-dimensioned nanomaterials/QW composite structure will be verified, the reason for improvement of the performance in these new devices compared with conventional planar devices will be illuminated, and the factors of influencing external quatum effieciency will be discussed. This project will provide a scientific reference for ZnO-based UV LEDs and other semiconductor light-emitting devices.

紫外发光二极管在光通信、日盲区探测、高密度存储、生物医疗等领域具有重大应用前景，但目前面临发光效率偏低及成本过高等问题。本项目拟采用具有宽直接带隙和高激子束缚能的ZnO作为紫外发光材料，将具有小尺寸效应、表面效应的纳米材料和具有量子限域效应的量子阱结合，达到缓解量子阱层间晶格失配、减弱阱内极化效应、增加有源层有效面积和提高出光效率等目的。本项目计划通过调控材料的能带结构、电学特性、晶体性质，参考器件仿真模拟结果，构筑基于一维纳米材料/量子阱复合结构的高量子效率、单色性好的ZnO紫外发光二极管。通过系统研究其光电特性，阐明发光来源与波长调控机制，探明一维纳米材料/量子阱复合结构情形下载流子输运与辐射复合发光过程，弄清该新型器件相对传统平面结构器件获得性能提升的原因并找出影响器件发光外量子效率的具体因素。申请人希望通过本项目的研究，为ZnO基紫外发光二极管及其他半导体发光器件研究提供科学参考。

紫外发光二极管在众多产业领域具有重大应用前景，但目前面临发光效率偏低、成本过高、我国核心专利技术缺乏等问题。本项目从材料研究出发，研制了具有良好晶体质量的ZnO等半导体薄膜材料，研制了高品质因子的掺杂ZnO透明导电薄膜，阐释了影响材料电学特性和光学特性的原因；研制了ZnO等半导体纳米材料，找出了影响形貌和其他物性的主要因素。在此基础上，设计研制了新型多量子阱结构和发光二极管器件，改善了载流子输运特性，提升了量子效率；将一维ZnO纳米材料应用于ZnO基紫外发光器件中，获得了高量子效率、单色性好的ZnO一维纳米材料/量子阱复合结构紫外发光二极管。项目研究结果表明，因多量子阱中空穴有效势垒的差异，将传统GaN体系发光二极管制备方案直接应用于ZnO基发光二极管中无法取得良好的发光性能。基于半导体能带理论和ZnO的材料特性，我们设计了组分渐变过渡层、梯度量子势垒等新型发光有源层结构，显著改善了多量子阱结构中的载流子输运特性，平衡了载流子浓度分布，提高了辐射复合速率，最终获得了发光效率的提升和大注入电流条件下量子效率衰减问题的改善。项目研究成果为以ZnO为代表的新型发光材料、发光器件领域研究提供科学参考和实践经验，为突破GaN基发光芯片专利保护壁垒、获得基于ZnO等新材料和新结构的具有自主知识产权的发光二极管芯片技术做出贡献。