高注入下GaN基紫光激光器的载流子输运及复合机制研究

GaN-based violet laser diodes have potential applications in the social and defense fields of high-density optical storage, biochemical detection, material process and missile proximity fuse. These applications demand low threshold voltage and high output light power of GaN-based laser diodes under high current density injection. Based on the characteristics of GaN-based laser diodes with emission wavelength in the violet region, such as the shallow quantum well, weak quantum-confinement and relatively greater probability to escape from the quantum wells and leak out, this proposal concentrate on the various mechanisms of carrier transport, recombination and leakage under different injection levels. The multi-coupled complex quantum wells are exploited to enhance the quantum confinement effect. The different leakage pathways of carriers in the multi-quantum well active region of laser diodes and corresponding adjustment methods are studied under high injection levels. Excess Mg atoms are doped in the p-GaN region to form deep-level defect and its related promoting effect to the transport processes of carriers across the p-doped region are theoretically investigated. The band structure of multi-quantum wells, AlGaN electron blocking layer and p-doped contact region are theoretically designed to optimize the carrier distribution and recombination under high injection levels. These theoretical and experimental results should benefit the development of GaN-based violet laser diodes with low threshold voltage and high output light power.

GaN基紫光激光器在高密度光存储、生化探测、材料加工等民用领域和在导弹近炸引信等国防领域均具有重要的应用前景，这些应用要求GaN基激光器在高注入状态下具有低阈值电压和高输出功率。本课题从GaN基激光器在紫光波段对应的量子阱较浅、限制作用较弱、阱中的载流子容易逸出并形成泄漏电流的特点出发，深入研究不同的注入水平下的载流子传输、复合和泄漏机制，包括多层耦合复杂量子阱结构对载流子限制作用的增强机制、高注入下激光器有源区内载流子的泄漏途径和调控手段、过量Mg掺杂在p-GaN中形成的深能级缺陷带和不同掺杂浓度下载流子在P型欧姆接触区域的输运过程等，通过对激光器的多量子阱有源区、电子阻挡层和P型掺杂区域的能带结构设计，以理论模拟和实验验证的方式实现对高注入状态下载流子分布和复合过程的功能调控，从而为实现低阈值电压、高输出功率的GaN基大功率紫光激光器提供理论基础和调控手段。

GaN基紫光激光器在高密度光存储、生化探测、材料加工等民用领域和在导弹近炸引信等国防领域均具有重要的应用前景，这些应用要求GaN基激光器在高注入状态下具有低阈值电压和高输出功率。本项目针对上述需求，进行了氮化镓基高功率紫光激光器的研制，在此研制过程中，对p型GaN的杂质补偿和高浓度掺杂、p-InGaN/p-GaN复合盖层中载流子的传输过程和高注入下有源区中电子泄漏机制等关系到器件性能的关键科学问题进行了深入研究。通过对GaN基激光器和GaAs基激光器的特性对比研究，对GaN大功率紫光激光器在高注入条件下的载流子传输、泄漏和复合机制进行了深入研究，从提高内量子效率的角度出发，对载流子的传输和复合过程进行功能调控，解决了GaN基紫光激光器MOCVD外延材料生长技术以及芯片制作技术、激光器封装等关键技术，研制出了高功率输出的GaN基紫光激光器。GaN基紫光脉冲激光器在频率10KHz、脉宽100ns、峰值电流为50A，激光器的峰值输出光功率达到27.5W，峰值波长是403.92纳米。GaN基紫光连续功率激光器在电流3.0A驱动下连续输出光功率达到2.7W,激光器两端的电压为5.04V。