基于纳米锥半极性面3D异质结构的InGaN绿光发光器件研究

In recent years, significant headway was made in the material epitaxy and device fabrication of nitride light-emitting diodes (LEDs). But so far, this has not significantly materialized in InGaN LED with high Indium components, such as green InGaN LED on commercial polar planar templates. The luminous efficiency and stability of the wavelength of this green InGaN LEDs, have been seriously restricted, by the adverse effects of high piezoelectric polarization electric fields and low crystal quality, which is inherent to the commercial green InGaN LEDs. However, the green InGaN hetero-structure LEDs on micro-nano three dimensional (3D) semi-polar templates are expected to solve the above problems, still based on the commercial polarized planar templates. The goal of this project is to have the green InGaN LED with uniform thickness and indium-composition of the quantum wells on 3D hexagonal-nanocone. We mainly focus on the controllable preparation, growth kinetics, and mass transport mechanism of the specialized 3D semi-polar green LEDs, which endow the InGaN hetero-structure with high controllability in Indium composition and hetero-structure thickness. Follow-up research might help reveal the underlying understanding of carrier injections, and transports, and thus mastering profoundly the intension of knowledge of physical mechanism of carrier Auger recombination, and the carrier leakage. Moreover, we would explore the design and configuration of the metal electrode of this special 3D structure LEDs to get a good ohmic contacts, thus with excellent current spreading. In the meantime, the high lighting extraction efficiency of this 3D structure green LED, will be achieved by the optimization of geometrical characteristics, such as the size, and the ratio of 3D structures. The project aims to get high efficiency 3D green LEDs, with stable wavelength.

近年来氮化物发光二极管（LED）的材料外延及器件制备已取得了十分重要的进展。但迄今为止，高In组分的LED主要采用二维平面极性异质结构，基于该结构的绿光LED难以同时较好的解决低压电极化电场与高晶体质量这两个问题，严重影响了绿光LED的发光效率和波长的稳定性。基于极性衬底的纳米锥半极性面三维（3D）异质结构有望解决以上问题。本项目拟基于申请者二维平面异质结构InGaN绿光LED研究的基础上，实现基于极性衬底的纳米锥3D异质结构均匀化可控外延及绿光LED的制备。研究纳米锥表面反应动力学特性和质量输运机制，实现In组分及材料厚度可控外延；深入分析载流子的注入、输运和复合规律，掌握俄歇复合、载流子泄漏的物理机制；探索在3D结构表面的金属电极的构型设计及蒸镀技术，获得良好的欧姆接触与电流扩展；深入研究3D微纳InGaN绿光LED阵列几何特征因素对光子提取的影响，制备出高光效、波长稳定的绿光LED。

本项目团队顺利完成了纳米锥半极性面3D异质结构的InGaN绿光发光器件研究。实现了基于极性衬底的纳米锥3D异质结构可控外延及微纳半极性面绿光LED的制备；系统研究了纳米锥表面外延生长InGaN多量子阱时原子的质量输运机制，实现了高生长温度下微纳半极性小面富In组分InGaN绿光多量子阱的外延生长；深入分析了纳米锥表面3D异质结构中载流子的注入、输运和复合规律，探索了绿光LED中俄歇复合、载流子泄漏的物理机制；在3D异质结构表面制备出金属电极，实现了3D绿光LED的电致发光；研究了3D微纳InGaN绿光LED阵列的光子提取，获得了较高的光提取效率。此外，我们还对本项目进行了拓展性研究，制备出了高空穴浓度的p-GaN材料。