Strain-Compensating Layers in Stacked Quantum Dot Active Regions

与量子阱（QW）激光器相比，在量子点（QD）晶体生长和器件设计方面取得了快速进展，可以产生更低的阈值电流密度，并提高了QD半导体激光器的温度稳定性。同样明显的是，量子点将在技术上具有重要的应用，如gaas基激光器的延长波长（1.0 mm- 1.3 mm）操作，以及对微腔应用（如低功率VCSELs和光子带隙缺陷激光器）很重要的横向电子载流子约束。基于子带间量子点跃迁的远红外激光器和光电探测器受到越来越多的关注。推进量子点技术的一个问题是，特别是在1.3 mm时，量子点有源区域的增益比量子点小。解决这个问题的方法是堆叠量子点层；然而，在外延中可以利用的应变材料的数量有很大的限制。本项目将研究包括应变补偿层的叠加量子点有源区域的发展，以平衡量子点堆叠的累积应变。应变补偿层的使用在应变多量子阱激光器领域是众所周知的，但尚未对堆叠量子点有源区域进行研究。这为材料和设备的新实验提供了一个很好的机会。该项目包括由拉伸应变InGa(As)P层分隔的多个压缩应变InGaAs/GaAs量子点活性层的晶体生长。通过x射线衍射和光致发光研究活性区以优化材料参数。虽然这项工作适用于由应变层外延形成的所有类型的量子点，但本项目将主要关注发射波长为1.3 mm的量子点。这些有源区域适用于单片1.3 mm gaas基vcsel，这对于通过二氧化硅光纤传输信号很重要。

0074528HuffakerRapid advances have been made in quantum dot (QD) crystal growth and device design to produce lower threshold current density and improved temperature stability in QD semiconductor lasers compared to quantum well (QW) lasers. It is also becoming evident that the QD will have technologically important applications such as extended wavelength (1.0 mm- 1.3 mm) operation of GaAs-based lasers and lateral electronic carrier confinement important for microcavity applications such as low power VCSELs and photonic bandgap defect lasers. Receiving increased attention are lasers and photodetectors operating in the far infrared based on intersubband QD transitions. One of the problems in advancing QD technology, especially at 1.3 mm, is the small gain in the QD active region compared to the QW. A solution to this problem is to stack the QD layers; however, there is a severe limitation on the amount of strained material which can be utilized in the epitaxy.This project will study the development of stacked quantum dot active regions which include strain compensating layers to balance the accumulated strain of the QD stacks. The use of strain-compensating layers is well known in the field of strained multiple quantum well lasers, however it has not yet been investigated for stacked quantum dot active regions. This presents a great opportunity for new experiments in both materials and devices. The project includes the crystal growth of multiple compressively strained InGaAs/GaAs quantum dot active layers separated by tensile strained InGa(As)P layers. The active regions will be studied through X-Ray diffraction and photoluminescence to optimize material parameters. Although the work is applicable to all types of QDs formed by strained layer epitaxy, this project will focus primarily on QDs which emit at the 1.3 mm wavelength. These active regions are applicable to monolithic 1.3 mm GaAs-based VCSELs which are important for signal transmission through silica fibers.