高可靠性高量子效率氮化镓基绿光激光器关键技术研究

Gallium nitride-based green laser has important scientific value and broad market prospects. Gallium nitride-based green laser has important application value in laser display, biomedicine, material processing, optical communication, optical storage, instruments and detection, image recording and other fields. However, the green laser needs further improvement in working life time, reliability and stability, and because of the strong polarized electric field in the active region of the green laser, the quantum efficiency of the green laser relatively lower than that of the blue-violet laser; the green laser needs to be prepared on the gallium nitride substrate; the defect density in the gallium nitride substrate directly determines the lifetime of the laser: the lower the defect density is, the longer the lifetime of the laser is. The project is based on low dislocation density GaN substrate preparation technology, using a new type of carbon nanotube material as a periodic dielectric mask, combined with lateral epitaxial technology and hydride vapor phase epitaxy to obtain low dislocation density gallium nitride material. At the same time, the physical structure of the device and the numerical simulation are used to design and optimize the high quantum efficiency strain-controlled active region structure of green laser, the new superlattice waveguide layer structure and the new confinement layer structure. Which will provide theoretical guidance and technical support for the development of high reliability and high quantum efficiency GaN-based green laser.

氮化镓基绿光激光器具有重要的科研价值及广阔的市场前景。氮化镓基绿光激光器在激光显示、生物医学、材料加工、光通讯、光存储、仪器和探测、图像纪录等领域具有重要应用价值。然而绿光激光器在工作寿命、可靠性及稳定性等方面还需要进一步改进，而且由于绿光激光器有源区受到较强的极化电场的影响，使得绿光激光器量子效率相对于蓝紫光波段的激光器较低；绿光激光器需要在氮化镓衬底上制备，氮化镓衬底材料中的缺陷密度高低直接决定了激光器寿命的长短：缺陷密度越低，激光器的寿命越长。本项目以低位错密度氮化镓衬底制备技术为基础，采用新型碳纳米管材料作为周期性介质掩膜，结合侧向外延技术及氢化物气相外延技术获得低位错密度氮化镓材料。同时利用器件物理模型和数值模拟的方法，设计和优化绿光激光器高量子效率应力调控有源区结构，新型超晶格波导层结构，新型限制层结构。进而为高可靠性高量子效率GaN基绿光激光器的研制提供理论指导和技术支持。

本项目在高可靠性高量子效率氮化镓基绿光激光器研制方面开展创新性研究工作，绿光激光器需要在氮化镓衬底上制备，氮化镓衬底材料中的缺陷密度高低直接决定了激光器寿命的长短：缺陷密度越低，激光器的寿命越长。本项目以低位错密度氮化镓衬底制备技术为基础，采用新型碳纳米管材料作为周期性介质掩膜，采用新型碳纳米管材料作为周期性介质掩膜，结合侧向外延技术获得低位错密度GaN外延层。在此基础上采用氢化物气相外延技术（HVPE）进行二次外延生长制备高晶体质量GaN同质衬底材料，制备高晶体质量GaN衬底材料。氮化镓单晶衬底CL测试结果显示，位错密度为4.4×10^(5)cm^(-2)。. 本项目利用器件物理模型和数值模拟的方法，设计和优化绿光激光器高量子效率应力调控有源区结构，光波导层结构以及限制层结构。从理论上给出设计优化的器件外延结构，以此为基础在低位错密度GaN衬底上进行绿光激光器的研制，研究突破绿光GaN基激光器的外延制备技术难点，深入研究生长温度，V/III比，反应室压力等参数对绿光激光器发光波长、晶体质量、表面形貌等参数的影响。根据具体的实验测试结果进行优化调整，实现实验结果和理论数值模拟的良性反馈。在低位错密度GaN衬底上制备GaN基绿光激光器外延材料，XRD测量可观测到5级以上的卫星峰; 绿光量子阱有源区内量子效率大于43.3%; 实现绿光激光器光泵激射，激射波长527.2nm。进而为高可靠性高量子效率GaN基绿光激光器的研制提供理论指导和技术支持。