晶面调制的半极性绿光LED量子效率提升关键技术研究

The project focuses on the key technique of semipolar GaN-based materials in the green LED technology which has shown promising applications. Based on previous researches of our group, we propose key techniques on the natural selection semipolar plane GaN on c-plane N-face GaN, surface dislocation density modulated semipolar plane GaN on c-plane Ga-face GaN, direction dependent dislocation coupled high quality semipolar GaN on m-plane sapphire. Particularly, focus on the use of the high-quality natural semipolar surface in N-plane structure, high quality large area of dislocations generated semipolar surface modulation, direction dependent coupling dislocations to improve the quality of the effective area of quantum wells. Numerical simulation study the coupling effect of doping, dislocations and stacking faults of various structures，provide an effective solution to the n-type and p-type doping problem of above described semipolar surface to improve the quantum efficiency. This study is expected to achieve high efficiency and high quality LED whole structures and provides a novelty and promising idea for semipolar GaN-based green LED applications.

本项目基于MOCVD技术，针对半极性GaN基材料在绿光LED技术中的广阔应用前景和全结构实现中所面临的关键技术难点，基于前期工作中所取得的研究成果，提出了包括c面蓝宝石衬底上N面GaN基的自选择半极性面、c面蓝宝石衬底上Ga面位错密度调制的半极性面、m面蓝宝石衬底上高质量GaN底板半极性GaN绿光LED器件全结构等关键技术，重点采用N面结构中自选择的高质量天然半极性面、位错调制产生的高质量大面积的半极性面、方向依存的位错耦合的高质量半极性面等创新性的关键技术来改善量子阱的有效面积和质量，通过数值仿真研究各种结构的掺杂、位错、层错的耦合作用，有效解决上述半极性面的n型和p型掺杂问题，最终实现量子效率的提升。开展本研究可望实现高效率、高质量的半级性LED结构，为半极性GaN基绿光LED的研究提供新思路。

本项目基于MOCVD技术，针对半极性GaN基材料在绿光LED技术中的广阔应用前景和全结构实现中所面临的关键技术难点，基于前期工作中所取得的研究成果，实现了包括c面蓝宝石衬底上N面GaN基的自选择半极性面、c面蓝宝石衬底上Ga面位错密度调制的半极性面。基于磁控溅射氮化铝技术，采用海浪式的生长方法得到了基于MOCVD技术的最高质量的GaN薄膜，XRD 002面和102面的半高宽只有58/90 arcsec，绿光LED的效率从13.0%提升到21.1%，提出了基于磁控溅射图形衬底上GaN薄膜位错湮灭的机理。采用斜切4°衬底，有效抑制了N面GaN结构中反型畴的形成，通过诱导In聚集的方式营造了镓极性GaN的半极性面，提高了发光面积，降低了量子限制斯塔克效应。