镓氮基高功率半导体激光器的红外缺陷及其热效应动力学研究

III-V semiconductor quantum well-based high-power diode lasers (HPLDs) as the man-made optoelectronic devices offer the most effective way of conversion from electrical energy into light with experimentally proved record values of beyond 70 percent. Despite the extremely high efficiency in such kind of devices, thermal heating due to the unconverted residual energy can lead to gradual and even sudden degradation including the catastrophic optical damage (COD), substantially influencing the stability and reliability of the devices and subsequently limiting the realization of the higher power output of the devices. Compared to the matured GaAs-based HPLDs, the GaN-based blue-laser devices represent the much lower output power in at least one order of magnitude (continuous-wave/cw several-Walts from a single-emitter). The material defects and the induced thermal effect in deices are extensively considered as the key factor, since they provide the non-radiative recombination channel for the electronically-injected non-equilibrium carriers. However, the origination of thermal in devices and its evolution mechanism are still unclear, especially when the defect emission from waveguide layers in GaAs-based semiconductor lasers is recently observed experimentally, which demonstrates the limitations of the currently well-accepted external COD model established based on the devices that have finished the degradation process. This project plans to focus on the defects in GaN-based semiconductor lasers (mainly with a single emitter structure) by utilizing the measurement condition-variable (temperature, steady-state and transient optical/electric fields, and so on), time- and spatial-resolved, separated-waveband emission spectroscopy (including photoluminescence/PL and electrical-luminescence/EL) and its thermal imaging information synchronizing detection system with the integration of the near-field scanning optical microscopy (NSOM) technique. We will investigate the emission mechanism of the short-wave infrared (SWIR) defects and the spectral and thermal imaging dynamics of the mid-wave infrared (MWIR) range under the steady-state and transient electric-injections. The processes of the injection, transport and recombination of the non-equilibrium carriers will be analyzed, in order to reveal the origination of the defects in devices, the spatial distribution and the evolution law of the induced-thermal effect, especially the lasing mechanism of the SWUR defect states and its competition relationship with the intrinsic power output from the quantum well layer of the devices. The physical reason why the bottle-neck effect of the output power exists in GaN-based devices will be explored in optics. These results could provide experimental guidelines for enhancing the COD-threshold value, the work stability and the quantum efficiency of this kind of devices.

高功率半导体激光器热效应会导致器件退化甚至灾难性光学损伤/COD，影响并制约器件更高功率输出。相较成熟的镓砷基激光器而言，镓氮基器件输出功率数量级偏低，材料缺陷及其引起的热效应是主要原因，但有关器件热起源及其演化机制不清晰、特别是近期有关腔体内部热动力学的实验观测，表明现有基于器件已发生退化所建立的外COD模型存在局限。项目拟结合近场扫描光学显微技术，利用变条件（稳瞬态光/电场）、时间和空间分辨的分波段发射谱及其热像同步探测系统，聚焦镓氮基量子阱激光器，研究稳/瞬态电注入调控器件COD时，器件的短波红外缺陷（自发和受激）辐射机制及其中波红外热像信息，分析非平衡载流子的注入、输运和复合过程，揭示器件缺陷来源、空间分布及其引起的热效应演化动力学、尤其是短波红外缺陷的受激发射及其与器件阱层本征功率输出的竞争机制，探索器件存在功率输出瓶颈的物理原因，为提高器件COD阈值、稳定性和效率提供实验指导。

高功率半导体激光器热效应会导致器件退化甚至灾难性光学损伤/COD，影响并制约器件更高功率输出。相较成熟的镓砷基激光器而言，镓氮基器件输出功率数量级偏低，材料缺陷及其引起的热效应是主要原因。项目首先聚焦镓氮基量子阱激光器，结合高集成多功能的时空分辨光电热谱技术，研究了稳/瞬态电注入调控器件COD时，器件的短波红外缺陷（自发和受激）辐射机制及其中波红外热像信息，分析了非平衡载流子的注入、输运和复合过程，揭示了器件缺陷来源、空间分布及其引起的热效应演化动力学、尤其是短波红外缺陷的受激发射及其与器件阱层本征功率输出的竞争机制，探索了器件存在功率输出瓶颈的物理原因和器件热起源及其演化机制，为器件性能优化提供了实验指导。同时，利用建立的光学手段对半导体薄膜太阳电池、铁性半导体、硅基通讯波段光源等体系进行了光电热学性质研究，相应地在提高电池效率、揭示新型铁性起源和光放大输出等方面获得了部分有创新意义的研究成果。