HgCdTe-based quantum-well-heterostructures for mid-infrared heterodyne spectroscopy

该提案团队的共同目标是研究并积极控制确定HgxCd 1-xTe/CdyHg 1-yTe多量子阱结构（MCT MQW）的光学和光电特性的物理机制，以应用于中红外（MIR，9 - 30微米）波长范围的外差光谱。中红外光谱带涵盖了许多重要的分子跃迁，例如在星际介质中。到目前为止，许多MIR应用依赖于MCT作为探测器的材料。可以通过有针对性地设计最先进的MCT MQW来改变和改善该材料的性能。它们的光谱响应由带隙决定，可以通过化学成分和晶格温度来改变，而电荷载流子能谱的设计和人工点缺陷的存在可以控制决定电子寿命的非平衡载流子的非辐射弛豫。控制MCT异质结构的寿命是设计和制造快速灵敏探测器以及外差光谱中混频器的基础。在这个项目中，我们希望开发针对9 - 30 µm MIR波段优化的MCT多量子阱，具有扩展的带宽或增强的操作速度。最终，该项目的目标是敏感的原型设备，并展示它们在快速时间分辨光谱学和敏感外差光谱学方面的性能。MQW异质结构的标准光学表征将与时间分辨光谱相结合，以获得有关材料中IR激发的动态和设备快速操作的基本限制的知识，这取决于主要由HgV中心控制的自由电子的特征寿命。最后，将在混频器原型中实现MCT多量子阱，以在外差光谱仪中演示和评估其性能

The common goal of the teams of this proposal is to investigate and to actively control the physical mechanisms determining the optical and optoelectronic properties of HgxCd1–xTe/CdyHg1–yTe-based multiple-quantum-well structures (MCT MQWs) towards applications in heterodyne spectroscopy in the mid-infrared (MIR, 9 - 30 micrometers) wavelength range. The mid-infrared spectral band covers many important molecular transitions, for example in the interstellar medium . Until now many MIR applications rely on MCT as material for detectors . The properties of this material can be varied and improved by design of state-of-the-art MCT MQWs in a targeted manner. Their spectral response, determined by bandgap, can be varied by chemical composition and lattice temperature, while designs of the charge carrier energy spectrum and presence of artificial point defects can control non-radiative relaxation of non-equilibrium carriers that determines electronic lifetimes. Controlling the lifetimes of an MCT heterostructure is the basis for designing and manufacturing fast and sensitive detectors as well as for mixers in heterodyne spectroscopy. In this project, we want to develop MCT MQWs optimized for the 9 – 30 µm MIR band with extended bandwidth or enhanced operation speed. Ultimately the project targets at sensitive prototype devices and demonstrating their performance for fast time-resolved spectroscopy as well as sensitive heterodyne spectroscopy. Standard optical characterization of the MQW heterostructures will be combined with time-resolved spectroscopy in order to obtain knowledge on the dynamics of IR excitations in the material and the fundamental limits for fast operation of the devices, which depends on the characteristic lifetimes of free electrons controlled dominantly by HgV centers. Finally the MCT MQWs will be will be implemented in the mixer prototypes for demonstrating and evaluating their performance in a heterodyne spectrometer