极化电场对III-V族氮化物半导体发光二极管载流子输运及器件内量子效率影响的研究

As the high-efficiency and energy-saving new lighting source, III-V nitride light-emitting diodes (LEDs) have received extensive research interest. However, the low carrier injection efficiency of the LEDs limits the internal quantum efficiency and causes the significant efficiency droop. According to the previous studies, the principal investigator (PI) of this research project finds that the carrier injection efficiency can be manipulated through engineering the polarization effect. Therefore, the PI has proposed a LED structure with the polarization-induced electron cooler and the hole accelerator incorporated in. A higher carrier injection efficiency can be enabled by manipulating the polarization level in the polarization-induced electron cooler and the hole accelerator. Nevertheless, the study on this aspect is rare until now. Therefore, with the aid of the numerical simulations and experimental approaches, a further study on the polarization-induced electron cooler and the hole accelerator is planned in this research project. Meanwhile, the electron unipolar field effect transistor (EUFET) and the hole unipolar field effect transistor (HUFET) are firstly proposed in this work to further understand the polarization effect on the carrier transport. This work is important in increasing the carrier injection, enhancing the internal quantum efficiency and reducing the efficiency droop for LEDs.

III-V族氮化物半导体发光二极管 (LEDs) 作为一种新型照明源已经得到广泛关注。然而LED的电子和空穴注入效率依然偏低，制约了器件内量子效率的进一步提升，并导致efficiency droop效应。在前期的研究工作中，申请人发现载流子的注入效率可以通过调节LED内部的极化场效应来提高。基于此，申请人提出一种拥有电子极化冷却层和空穴加速器的LED结构。通过调节极化冷却层和空穴加速器内部的极化场机制，载流子的注入效率可以得到改善。然而极化冷却层和空穴加速器的研究工作目前尚处于初期阶段，在该课题的研究中，我们拟用理论模拟结合实验测量的方式，进一步阐述极化场在提升载流子注入效率方面的促进作用；同时，本课题首次提出的单极电子场效应晶体管和单极空穴场效应晶体管有助于直接表征载流子输运与极化场之间的关系。该研究领域的探索对于进一步提升载流子的注入效率，提高LED器件的内量子效率具有重要意义。

氮化物发光二极管(LED)具备能耗低、寿命长、无污染、效率高等优点，目前已经逐步取代荧光灯。氮化物LED的电子和空穴注入不平衡，这对于目前关注度较高的AlGaN基深紫外发光二极管(DUV LED)而言更加突出，本项目围绕基金既定目标，同时又适度扩展，对LED电子冷却、LED空穴加速、极化电场调控的电子器件展开研究，取得重要研究成果。.建立并完善APSYS仿真代码，调试物理模型和物理参数，通过与实验数据对比，建立关于电子注入、空穴注入的脚本文件；根据脚本文件，课题组分析电子能量对电子注入效率的影响、空穴能量对空穴注入效率的影响，同时课题组提出了相关LED器件结构，利用MOCVD技术和半导体器件工艺手段，制备LED芯片；利用项目负责人提出的结构，LED器件的电子注入效率得到了大幅改善，同时外量子效率得到显著提升。.除了探索传统架构的LED之外，课题组还研究了核壳结构纳米LED，探索了极化场强度、纳米柱高度、核层厚度等因素对核壳纳米LED载流子输运、外量子效率、电流扩展等重要指标的影响，建立了仿真物理模型，揭示了核壳结构纳米LED的器件物理。.项目负责人总结了影响氮化物LED外量子效率的各个因素，并对相应的物理机制进行总结和概括，应邀撰写邀请综述论文4篇，图书章节3章 (Handbook of GaN Semiconductor Materials and Devices, Handbook for Solid-State Lighting and LEDs，出版社为CRC Press, Taylor & Francis Group；Light-Emitting Diodes – Materials, Processes, Devices and Applications，出版社为Springer)，学术专著 1部(题目为：Deep ultraviolet LEDs - understanding the low external quantum efficiency)。.本项目的研究成果对于丰富氮化物LED基础理论，完善半导体器件物理具有重要意义；同时本项目提出的多个氮化物LED器件架构改善了外量子效率、降低了正向导通电压，对于实现高亮度氮化物LED具有重要的推动作用；本项目所提出的解决方案无论对于学术界还是工业界来说都意义重大。