Research on Blue and Near Ultraviolet Diode Lasers

9726938努尔米科研究所提出了一项研究计划，其目标是专注于基础和应用半导体科学的特定领域，以帮助继续开发基于氮化物的第三类半导体蓝光激光器，并将此类设备扩展到近紫外线。在这一技术潜力巨大的领域取得进一步进展需要系统的科学努力。PI确定并解决了拟议计划中的两个关键领域：(A)研究氮化物量子阱中的光学增益和相关辐射过程，以优化激光器的有源区并实施低阈值器件设计，以及(B)在微观层面上对p型欧姆接触问题的理解。除了宽禁带半导体的整体特性外，这两个问题领域都受到氮化物异质结构复杂而丰富的微结构的影响。因此，在计划的工作中，我们还寻找晶体微结构和光电性能之间的关键联系，目前对这些联系知之甚少。除了我们在氮化物基二极管发光器方面的早期成果外，PI还利用了我们在蓝绿II-VI半导体激光器方面的经验，在这些经验中，PI成功地解决了增益、器件设计和接触问题，以推动这些量子井二极管器件的发展。当然，氮化物中确实存在显著的差异和明显的挑战；然而，鉴于宽禁带半导体在基本层面上的共同特征为定量和具有科学意义的比较提供了非常有用的比较基础，拟议的研究利用了适用于氮化物异质结构和半导体激光器件研究的特殊能力和技术。例如，先进的基于激光的光谱技术，包括超快实时光谱，将被应用于研究无序系统中高密度低维电子-空穴对的光学增益和动力学，例如在InGaN量子阱中，电子局域效应是重要的。这些技术包括高空间分辨率的探测器，如近场光学显微镜。对于p型接触的研究，提出了在超高真空环境下原位沉积金属化和InN异质结作为研究金属-氮化物界面微观性质的一种手段，以优化用于半导体激光器应用的低阻接触。***

9726938 Nurmikko The PI proposes a research program whose objective is to focus on specific areas of basic and applied semiconductor science to aid in the the continued development of the group III-nitride based semiconductor blue lasers and extension of such devices to the near ultraviolet. Further progress in this field of vast technological potential requires systematic scientific efforts. The PI identifies and addresses two critical areas in the proposed program: (a) the study of optical gain and related radiative processes in the nitride quantum wells for optimizing the active region of the laser and implementing a low threshold device design, and (b) development of understanding at a microscopic level of the p-type ohmic contact problem. In addition to the overall idiosyncracies of a widegap semiconductor, both of these problem areas are impacted by the complex and rich microstructure of the nitride heterostructures. In the planned work we thus also look for key links between the crystal microstructure and optoelectronic properties which are presently poorly understood. Apart from our early results on nitride-based diode light emitters, the PI takes advantage of our experience with bluegreen II-VI semiconductor lasers where the issues of gain, device design, and contacts were successfully pursued by the PIs for advancing these quantum well diode devices. Significant differences and distinct challenges do, of course, exist in the nitrides; however, given the common features that are shared by wide bandgap semiconductors at a fundamental level provides a very useful base of comparison for quantitatively and scientifically meaningful comparisons, The proposed research takes advantage of special capabilities and techniques adapted to the study of both nitride-based heterostructures and diode laser devices. For example, advanced laser-based spectroscopic techniques, including ultrafast real-time spectroscopy will be applied to study the optical gain and dynamics of a high density lo w dimensional electron-hole pair in a disordered system such as the InGaN QW where electronic localization effects are important. The techniques include high spatial resolution probes such as near-field optical microscopy. For the p-type contact studies, in-situ deposition of metallization and InN heterostructures in UHV environment is proposed as a means to study the microscopic properties of the metal-nitride interface in order to optimize a low resistance contact for diode laser application. ***