High Efficiency Diode Lasers based on Nanopatterned Quantum Dot Active Regions

“这项奖励是根据2009年美国复苏和再投资法案（公法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。不幸的是，理想量子点有源层的这些独特特征至今尚未完全实现。迄今为止最成功的形成量子点的方法是在Stranski-Krastanow （SK）生长模式下的自组装。然而，这种方法导致量子点尺寸分布相对较大，导致光谱增益的显着不均匀展宽。SK量子点固有地形成在二维“润湿层”的顶部，导致弱电子和空穴限制到量子点，这导致低增益饱和。在这里，我们采用致密的纳米级二嵌段共聚物光刻技术，消除了润湿层状态，提高了量子点尺寸的均匀性。智力优势：智力优势在于，这些结构将首次允许研究近理想（即完整的3D量子限制）量子点有源区域的光学增益特性，提高对量子点载流子重组机制、光学增益和辐射效率的理解。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各个方面，从设计到制造和表征。学生将有机会使用威斯康星大学麦迪逊分校最先进的晶体生长设备和广泛的材料表征技术来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.