High Efficiency Diode Lasers based on Nanopatterned Quantum Dot Active Regions

该奖项是根据2009年美国复苏和再投资法案(公共法律111-5)资助的。量子点(QD)有源区具有实现极高性能半导体二极管激光器的潜力。遗憾的是，理想的量子点有源层的这些独特功能到目前为止还没有完全实现。到目前为止，形成量子点最成功的方法是在斯特兰基-克拉斯塔诺(SK)增长模式下的自组装。然而，这种方法导致了相对较大的量子点尺寸分布，导致光谱增益的显著不均匀展宽。SK量子点固有地形成在二维“润湿层”的顶部，导致弱电子和空穴对量子点的限制，从而导致低增益饱和度。在这里，我们采用基于致密纳米级两嵌段共聚物光刻技术的纳米制造，它消除了润湿层状态并改善了量子点尺寸的均匀性。智能化的优点：这些结构将首次允许研究近理想(即完全3D量子限制)量子点有源区的光增益特性，提高对载流子复合机制、光增益和量子点辐射效率的理解。这些研究的广泛影响包括首次实现功率转换效率超过80%的紧凑型二极管激光光源，大大降低了高输出功率应用的功耗。更广泛的影响：教育的广泛影响是研究生将学习光电子器件工程的方方面面，从设计到制造和表征。学生将有机会接触到威斯康星大学麦迪逊分校最先进的晶体生长设施和广泛的材料表征技术，以评估量子点的光学和结构质量。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Quantum dot (QD) active regions hold potential for realizing extremely high performance semiconductor diode lasers. Unfortunately, these unique features of ideal QD active layers have not been fully realized to date. The most successful approach to date of forming QD's are self-assembly under the Stranski-Krastanow (SK) growth mode. However, this approach results in a relatively large distribution of QD sizes, leading to significant inhomogeneous broadening of the spectral gain. SK QDs inherently form on top of a two-dimensional 'wetting layer', leading to weak electron and hole confinement to the QD, which results in low gain saturation. Here, we employ dense nanoscale diblock copolymer lithography-based nanofabrication which eliminates the wetting layer states and improves QD size uniformity.Intellectual Merit:The intellectual merit is that these structures will allow for the first time the study of the optical gain characteristics of near ideal (i.e. complete 3D quantum confinement) QD active regions, improving understanding carrier recombination mechanisms, optical gain, and radiative efficiency of QDs. The broad impact of such studies encompasses the first realization of compact diode laser sources with power conversion efficiencies in excess of 80%, drastically reducing power consumption for high output power applications. Broader Impacts:The educational broad impact is that graduate students will learn all aspects of optoelectronic device engineering, from design to fabrication and characterization. Students will have access to state-of-the-art crystal growth facilities at UW-Madison and extensive material characterization techniques to assess the optical and structural quality of the quantum dots.