Investigation of fundamental physical properties of coupled quantum well - quantum dot systems emitting in the near infrared range of 1.3 - 1.55 micrometer (Acronym: QuCoS = Quantum Coupled Systems).

本研究的主题是研究耦合的二维(量子井)和零维(量子点)半导体量子子系统的基本物理性质，这些量子子系统以近红外(1.3-1.55 nm)光谱范围内的基态光子发射波长为特征。该项目的主要目的是对几个密切相关的问题进行理论和实验研究，以获得关于以下方面的知识：-(I)重要的物理相互作用，这可以解释空间分离但仍以量子力学耦合的量子井(QW)和量子点(QD)子系统(例如电子/空穴-光学/声学声子、激子-激子或载流子-载流子相互作用过程)之间的非共振电荷/激子/自旋转移；-(Ii)量子波耦合量子点系统中的载流子/激子/自旋弛豫路径，这主要取决于弛豫散射过程的耦合强度和效率；-(Iii)系统中的材料组成/应变对俄歇过程和俄歇辅助量子阱与量子点之间的载流子转移效率的影响；-(Iv)控制量子波和量子点之间量子力学耦合强度的可能性，考虑到例如：温度、载流子/激子布居、半导体材料的化学含量及其电子结构；-(V)量子波耦合量子点系统中电荷/激子/自旋转移的相干和非相干动力学性质，随后是光学注入/自旋初始化过程及其控制；-(Vi)耦合量子波和量子点系统的自旋相关性质。我们要验证的假设是，通过仔细选择物理相互作用和半导体材料的性质，人们可以设计和制造一个具有广泛和精确可控的电荷/激子/自旋从量子波到量子基态的转移效率的量子系统，两者都在真实空间中分离，同时保持三个条件：(I)量子基态是整个耦合系统的最低能级，(Ii)它保持其局域性(原子性质)，以及(Iii)在1.3-1.55微米的近红外光谱范围内发射光子。&gt；&gt；作为一个长期目标，我们预计我们的调查结果将指出与设计具有所需参数的耦合量子波-量子点系统相关的最关键的问题。我们打算验证不同维度的空间分离的子系统之间的量子力学耦合的作用，并演示如何在基本的物理水平上控制它。这一知识可能用于开发参数优越的新型光电子器件和自旋电子器件(即快速调制激光器、开关、长存储时间和快速读/写存储器等)，其依赖于QW耦合的QD系统架构。

The subject of this research is to investigate the basic physical properties of coupled two-dimensional (quantum well) and zero-dimensional (quantum dots) semiconductor-based quantum subsystems characterized by the ground state photon emission wavelength in the near-infrared (1.3-1.55 um) spectral range. >>>> The major aim of the project is to perform the theoretical and experimental studies of several closely related issues in order to acquire the knowledge on: ---- (i) important physical interactions, which can account for a non-resonant charge/exciton/spin transfer between spatially separated but still quantum-mechanically coupled quantum well (QW) and quantum dot (QD) subsystems (e.g. electron/hole-optical/acoustic phonon, exciton-exciton or carrier-carrier interaction processes); ---- (ii) carrier/exciton/spin relaxation pathways in the QW-coupled-QD system which should primarily depend on the coupling strength and efficiency of relaxation-mediated scattering processes; ---- (iii) the influence of material composition/strain in the system on the efficiency of Auger process and Auger-assisted carrier transfer between the quantum well and the dots; ---- (iv) possibilities to control the strength of the quantum-mechanical coupling between QW and QD, taking into account such factors as e.g.: temperature, carrier/exciton population, chemical content of semiconductor materials and their electronic structure; ---- (v) coherent and incoherent dynamic properties of charge/exciton/spin transfer followed by optical injection/spin initialization process and its control in the QW-coupled-QD system; ---- (vi) spin-related properties of a coupled QW and QD system. >>>> The hypothesis we intend to verify is that by a careful selection of physical interactions and semiconductor material properties one can design and produce a quantum system with widely and precisely controllable efficiency of charge/exciton/spin transfer from a QW to the QD ground state, both separated in the real space, while keeping three conditions: (i) the QD ground state is the lowest energy state for an entire coupled system, (ii) it keeps its localized character (atomic-like character), and (iii) emits photons in the near-infrared spectral range of 1.3-1.55 um. >>>> As a long-term objective, we anticipate that the results of our investigation will point out the most critical issues related to a design of the coupled QW-QD systems of desired parameters. We intend to verify the role of a quantum mechanical coupling between spatially separated subsystems of different dimensionality and demonstrate how to control it on the basic physical level. This knowledge will possibly be used in the development of novel optoelectronic and spintronic devices of superior parameters (i.e. fast modulated lasers, switches, long storage time and fast read/write memories etc.), which rely on the QW-coupled-QD system architecture.