Collaborative Research: Study of Strain-Dependent Auger Recombination Processes in III-V Materials Using Membranes

非技术描述：俄歇复合是一种降低光电子器件(从激光器和发光二极管到太阳能电池和光电探测器)的III-V材料性能的过程。特别是，在电磁光谱的中红外区域发射光的激光器受到俄歇复合的严重影响。中红外激光在传感、自由空间通信和医学方面非常重要。科罗拉多大学博尔德分校和德克萨斯大学奥斯汀分校的这一合作研究项目旨在了解和控制III-V材料中的俄歇复合过程，以最终提高中红外激光器的性能。研究工作与教育活动很好地结合在一起。这些努力包括为研究生和本科生提供跨学科的研究机会，将研究成果与大学课程相结合，以及通过光学相关模块扩展K-12。技术描述：应变可以大大减少III-V材料中量子受限有源区的俄歇重组的负面影响。然而，应变对复合过程影响的基本理解一直受到应变施加的临界厚度限制的阻碍，这使得分析变得复杂，并且经常需要不切实际的近似。该合作项目通过检查材料的活性应变区，对与理解和表征复合过程相关的挑战采取了正交方法。具体地说，由III-V材料制成的半导体膜从其宿主衬底上释放并结合到柔性聚合物上。通过在两个维度上拉伸聚合物衬底来模拟晶格失配生长所产生的双轴应变的效果来对膜进行双向应变。这使得可以在单个样品上使用超快光谱对俄歇重组进行与应变相关的研究，将应变的内在效应与由于成分变化或生长动力学引起的内在效应隔离开来。这项研究可能会揭示俄歇和其他损耗过程在III-V材料系统中的作用，这是器件和材料界持续30年的争论，并使高效率二极管激光器和发光二极管能够在可见范围内工作。

Nontechnical Description: Auger recombination is a process that degrades the performance of III-V materials for optoelectronic devices, ranging from lasers and light-emitting diodes, to solar cells and photodetectors. In particular, lasers emitting light in the mid-infrared region of the electromagnetic spectrum are impacted heavily by Auger recombination. Mid-infrared lasers are important for sensing, free-space communications, and medicine. This collaborative research project between the University of Colorado at Boulder and the University of Texas at Austin seeks to understand and control the Auger recombination process in III-V materials to ultimately enhance the performance of mid-infrared lasers. The research efforts are well integrated with the educational activities. The efforts include providing interdisciplinary research opportunities to graduate and undergraduate students, integrating research findings with college coursework, and K-12 outreach through optics-related modules.Technical Description: Strain can greatly reduce the negative effects of Auger recombination in quantum confined active regions in III-V materials. However, the fundamental understanding of the strain effects on the recombination processes has been hindered by the critical thickness limitations imposed by strain, complicating analysis and often necessitating unrealistic approximations. The collaborative project takes an orthogonal approach to the challenges associated with understanding and characterizing recombination processes by examining the active strained regions of the materials. Specifically, semiconductor membranes made of III-V materials are released from their host substrate and bonded to a flexible polymer. The membranes are biaxially strained by stretching the polymer substrate in two dimensions to mimic the effect of biaxial strain from lattice-mismatched growth. This permits strain-dependent studies of Auger recombination using ultrafast spectroscopy on a single sample, isolating the intrinsic effects of strain from those due to compositional change or growth kinetics. This study could shed light on the roles of Auger and other loss processes in III-V material systems, an ongoing 30+ year debate across the device and materials communities, and enable high-efficiency diode lasers and light-emitting diodes in visible regime.