One-dimensional carrier systems in nanowire-based semiconductor heterostructures

基于纳米线的半导体异质结构中的一维载流子系统

• 批准号: 323412876
• 负责人: Privatdozent Dr. Gregor Koblmüller
• 金额: --
• 依托单位: Walter Schottky Institut für physikalische Grundlagen der Halbleiterelektronik (WSI)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/323412876?language=en
• 关键词: dimensional; carrier; systems; nanowire; based

The two major goals of this project are the realization of advanced one-dimensional quantum confined semiconductor heterostructures on an inherently one-dimensional nanowire platform and the correlation of their structural, optical and electrical transport properties.For the growth using molecular beam epitaxy, we pursue two independent routes to implement true quantum confined one-dimensional carrier systems. While the controlled synthesis of quantum-confined two-dimensional quantum wells and zero-dimensional quantum dots has been established recently, one-dimensional quantum wires have remained the final missing element, despite the inherently one-dimensional geometric nature of the nanowire template.Moreover, the paradigm of strain engineering, key for a myriad of devices based on planar heterostructures has to be transferred to nanowires. However, their one-dimensional geometry allows for efficient strain relaxation. Thus, radically new strategies for strain engineering are required to fully exploit the potential of this yet almost unexplored key tuning parameter.Our approach to realize such quantum wires is based on the GaAs-based material systems using (i) diameter-controlled ultra-thin nanowire cores and (ii) radial multi-shell nanowire heterostructures. Such synthesized heterostructure nanowires are characterized on one side with respect to their structural (crystal structure, defects, chemical composition, strain) and their quantized energy spectrum. On the other side, we access the native transport characteristics of different confined carrier systems in the nanowire by optically probing the spatio-temporal carrier dynamics induced by a surface acoustic wave with high spatial and temporal resolution and numerical simulations.Finally, the direct correlation of the results of this contact-less electrical and optical characterization and that of structural investigations will reveal the underlying interconnections between the local microstructural (interface roughness, mixing of different crystal phases, alloy composition, strain) and electrical properties within single nanowires.From these complementary and correlation studies we will derive strategies for the optimization of tailored heterostructure nanowires for device application. In particular, we aim to tailor the valence band structure in these systems by static epitaxial strain. Using acousto-optical spectroscopy we aim to demonstrate a strain-induced light hole ground state with improved electric transport properties arising in a dramatic increase of the hole mobility.

本项目的两个主要目标是在固有的一维纳米线平台上实现先进的一维量子限制半导体异质结构，以及它们的结构、光学和电输运性质的相关性。对于分子束外延的生长，我们追求两种独立的途径来实现真正的量子受限一维载流子系统。虽然最近已经建立了量子受限二维量子阱和零维量子点的受控合成，但一维量子线仍然是最后缺失的元素，尽管纳米线模板具有固有的一维几何性质。此外，应变工程的范例，关键是基于平面异质结构的无数器件必须转移到纳米线。然而，它们的一维几何结构允许有效的应变松弛。因此，需要全新的应变工程策略来充分利用这一几乎未开发的关键调谐参数的潜力。我们实现这种量子线的方法是基于gaas基材料系统，使用(i)直径控制的超薄纳米线芯和（ii）径向多壳纳米线异质结构。从结构（晶体结构、缺陷、化学成分、应变）和量子化能谱等方面对合成的异质结构纳米线进行了表征。另一方面，通过光学探测高时空分辨率表面声波诱导的时空载流子动力学，并进行数值模拟，研究了纳米线中不同受限载流子系统的固有输运特性。最后，这种非接触电学和光学表征结果与结构研究结果的直接相关性将揭示单根纳米线内部局部微观结构（界面粗糙度、不同晶相的混合、合金成分、应变）和电学性能之间潜在的相互联系。从这些互补性和相关性研究中，我们将推导出用于器件应用的定制异质结构纳米线的优化策略。特别是，我们的目标是通过静态外延应变来定制这些体系中的价带结构。利用声光光谱，我们的目标是证明应变诱导光空穴基态在空穴迁移率的急剧增加中具有改善的电输运性质。