Dynamics of Fundamental Optical Transitions in Gallium Nitride and Aluminum Gallium Nitride

本研究项目旨在研究GaN和AlGaN中带到带激子的动力学，以及带到杂质的转变，包括重组寿命和量子效率，采用时间分辨光致发光光谱测量。这些动态过程将在外延层、异质结构、量子阱和不同条件下的人工结构激光腔中进行研究——温度、激发能、强度和极化。基本重要的物理量，包括决定激发、吸收和复合等基本光学过程的自由激子和束缚激子振荡器强度，将被测量。生长后退火、外场和合金成分对光学复合动力学的影响将包括在研究中。此外，还将研究光泵浦受激发射和激光条件下的光跃迁动力学，以确定激光应用中优选的光跃迁信息，并为GaN激光器的增益机制和量子效率提供模型描述。在宽禁带半导体光学器件中，如紫外发射器和紫外蓝光激光二极管，基本光学跃迁的动态过程是决定其性能的主要因素。GaAs和ZnSe半导体激光器的发展历史表明，了解基本的光学复合动力学是理解激光活性的重要关键。此外，了解光学跃迁的动态过程为提高材料质量提供了新的方向，对光电器件的设计和优化具有重要价值。该研究将在与先进光子学的几个方面相关的基础技术水平上贡献基础材料科学知识。此外，从本研究项目中获得的知识和理解有望通过为设计和生产改进材料提供基本的理解和基础，以一般方式改善用于计算，信息处理和电信的先进设备和电路的性能。该计划的一个重要特点是通过培养学生在一个基础和技术上重要的领域的研究和教育的整合。＊＊＊

9528226 Lin This research project is targeted at the investigation of the dynamics of band-to-band exciton, and band-to-impurity transitions in GaN and AlGaN, including recombination lifetimes and quantum efficiencies, employing time-resolved photoluminescence spectroscopy measurements. These dynamic processes will be investigated in epitaxial layers, heterostructures, quantum wells, and artificially structured laser cavities under different conditions--temperature, excitation energy, intensity, and polarization. Fundamentally important physical quantities, including the free- and bound-exciton oscillator strengths which determine basic optical processes such as excitation, absorption, and recombination, will be measured. The effects of post-growth annealing, external fields, and alloy composition on the optical recombination dynamics will be included in the study. In addition, the dynamics of optical transitions will be investigated under conditions of optically-pumped stimulated emission and lasing to ascertain information regarding preferable optical transitions for laser applications as well as to provide model descriptions for gain mechanisms and quantum efficiencies in GaN lasers. %%% In wide bandgap semiconductor optical devices, such as UV emitters and UV-blue laser diodes, it is the dynamic processes of the fundamental optical transitions that predominantly determine their performance. The history of GaAs and ZnSe semiconductor laser development shows that understanding fundamental optical recombination dynamics is an important key to the understanding of laser activity. Additionally, an understanding of the dynamic processes of optical transitions provides new directions for improving material quality as well as being of great value in designing and optimizing optoelectronic devices. The research will contribute basic materials science knowledge at a fundamental level of technological relevance to several aspects of advanced photonics. Additionally, the knowledge and understandin g gained from this research project is expected to contribute in a general way to improving the performance of advanced devices and circuits used in computing, information processing, and telecommunications by providing a fundamental understanding and a basis for designing and producing improved materials. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***