Research on Blue and Near Ultraviolet Diode Lasers

PI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iii族氮化物半导体蓝色激光器的持续发展，并将此类设备扩展到近紫外。在这一具有巨大技术潜力的领域取得进一步进展需要系统的科学努力。PI确定并解决了计划中的两个关键领域：(a)研究氮化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域并实现低阈值器件设计，以及(b)在微观层面上发展对p型欧姆接触问题的理解。除了宽隙半导体的整体特性外，这两个问题区域都受到氮化物异质结构复杂而丰富的微观结构的影响。因此，在计划的工作中，我们也寻找晶体微观结构与目前知之甚少的光电特性之间的关键联系。除了我们在氮基二极管光源上的早期成果外，PI还利用了我们在蓝绿色II-VI半导体激光器方面的经验，其中PI成功地追求了增益，器件设计和触点问题，以推进这些量子阱二极管器件。当然，氮化物中确实存在显著的差异和明显的挑战；然而，考虑到宽带隙半导体在基础水平上的共同特征，为定量和科学上有意义的比较提供了非常有用的比较基础，所提出的研究利用了适用于氮基异质结构和二极管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学技术，包括超快实时光谱学，将应用于研究无序系统（如InGaN QW）中高密度低维电子-空穴对的光学增益和动力学，其中电子局域化效应很重要。这些技术包括高空间分辨率探针，如近场光学显微镜。对于p型接触研究，提出了在特高压环境下原位沉积金属化和InN异质结构作为研究金属-氮化物界面微观性质的手段，以优化用于二极管激光的低电阻接触。＊＊＊

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. ***