Strain-Compensating Layers in Stacked Quantum Dot Active Regions

与量子井(QW)激光器相比，量子点(QD)半导体激光器在量子点(QD)晶体生长和器件设计方面取得了快速进展，产生了更低的阈值电流密度和更高的温度稳定性。此外，量子点还将在技术上具有重要的应用，如扩展波长(1.0 mm-1.3 mm)的GaAs基激光器，以及对微腔应用(如低功率VCSEL和光子带隙缺陷激光器)非常重要的横向电子载流子限制。基于子带间量子点跃迁工作在远红外的激光器和光电探测器受到越来越多的关注。发展量子点技术的一个问题是，与量子点相比，量子点有源区的增益很小，尤其是1.3 mm处。解决这一问题的一种方法是堆叠量子点层，但可用于外延的应变材料的数量存在严重限制。本项目将研究包括应变补偿层的堆叠量子点有源区的开发，以平衡量子点堆栈的累积应变。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，但对于堆积量子点有源区还没有被研究过。这为材料和器件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层隔开的多个压缩应变InGaAsGaAs量子点有源层的晶体生长。通过X射线衍射法和光致发光法对活性区域进行研究，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，但该项目将主要关注在1.3毫米波长发射的量子点。这些有源区适用于单片1.3 mm的GaAs基垂直腔面发射激光器，这些器件对于通过石英光纤传输信号非常重要。

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.