GaN基激光器多量子阱垒材料的研究

Research on AlInGaN Quaternary Alloys as MQW Barriers in GaN-Based Laser Diodes

在(0001)蓝宝石衬底上分别用金属有机化学气相沉积技术外延生长了InGaN/GaN,InGaN/In-GaN,InGaN/AlInGaN多量子阱激光器结构,并分别制作了脊形波导GaN基激光器。同步辐射X射线衍射,电注入受激发射光谱测试及光功率-电流(L-I)测试证明,相对于GaN垒材料,InGaN垒材料,AlInGaN四元合金垒材料更能改善多量子阱的晶体质量,提高量子阱的量子效率及降低激光器阈值电流。相关的机制为:组分调节合适的四元合金垒层中Al的掺入使得量子阱势垒高度增加,阱区收集载流子的能力增强;In的掺入能更多地补偿应力,减少了由于缺陷和位错所产生的非辐射复合中心密度;In的掺入还减小了量子阱中应力引致的压电场,电子空穴波函数空间交叠得以加强,使得辐射复合增加。

InGaN/GaN, InGaN/InGaN and InGaN/AIlnGaN multi-quantum-well （MQW） laser diodes （LDs） were grown on （0001） sapphire substrate by metalorganic chemical vapor deposition （MOCVD）. The GaN （0002） synchrotron X-ray diffraction （XRD）, electroluminescence （EL） and optical power-current （L-I） measurement reveal that AIlnGaN quaternary alloys as barriers in MQWs can improve the crystal quality, optical emission performance, threshold current and slope efficiency of the laser diode structure to a large extent compared with other barriers. The relevant mechanisms are that： 1. The AI component increases the barrier height of the MQWs so that more current carriers will be caught in. 2. The In component counteracts the strain in the MQWs that decreases the dislocations and defects, thereby the nonradiative recombination centers are decreased. 3. The In component decreases the piezoelectric electric field that makes the electrons and the holes recombine more easily.