Total Tomography of III-V Non-Planar Heterostructures

非技术描述：半导体材料，特别是由III族和V族元素组成的合金，在发光二极管器件中将电能转换为光是有用的。不同的III-V半导体可以在异质结构中组合，使器件更小，能量转换过程更高效。该项目发展了对纳米线形式的半导体合金如何最好地排列以控制电能流动并产生红外光谱部分的光的基本理解。这种理解有助于片上光子互连的发展，克服了在云计算中处理大量信息的计算机芯片之间信息传输速度的瓶颈。该项目在西北大学和国家实验室培养尖端三维表征方法的研究生。基于网络的交互式案例研究用于传播这些表征方法的进展，这可以加速新的电子和光子技术的发展。技术描述：该项目的目标是在三维上关联III-As族纳米线核壳异质结构的成分、应变和电子结构，以了解成分和应变之间的相互作用如何影响纳米结构的生长和光电子特性。原子探针层析成像用于测量纳米级分辨率的三维成分场。基于这些成分数据，建立了松弛物理结构的有限元模型，从单纳米线x射线成像和衍射研究中提取三维应变信息。结合应变和成分数据，包括只能通过原子探针断层扫描获得的掺杂分布，用于模拟电子和光学特性，并确定限制III-As核壳纳米线作为红外发光二极管和激光器性能的材料因素。单纳米线拉曼、光致发光和电测量用于空间映射应变、载流子浓度和寿命，以及建立约束电位的带偏移。

Nontechnical description: Semiconducting materials, particularly alloys composed of group III and group V elements, are useful for converting electrical energy to light in light-emitting diode devices. Different III-V semiconductors can be combined in heterostructures to make devices smaller and the energy conversion processes more efficient. The project develops fundamental understanding of how semiconducting alloys in nanowire form can be best arranged to control the flow of electrical energy and generate light in the infrared portion of the spectrum. This understanding contributes to the development of on-chip photonic interconnects that overcome the bottleneck in the speed of information transfer between computer chips that process huge volumes of information in cloud computing. The project trains graduate students in cutting-edge three-dimensional characterization methods at Northwestern and in national laboratories. Web-based interactive case studies are used to disseminate advances in these characterization methods, which can accelerate the development of new electronic and photonic technologies.Technical description: The goal of the project is to correlate the composition, strain, and electronic structure of group III-As nanowire core-shell heterostructures in three dimensions to understand how interactions between composition and strain influence nanostructure growth and optoelectronic properties. Atom probe tomography is used to measure three-dimensional composition fields with nanoscale resolution. Based on these composition data, finite element models of relaxed physical structure are created to extract three-dimensional strain information from single nanowire x-ray imaging and diffraction studies. Combined strain and composition data, including dopant distributions accessible only by atom probe tomography, are used to model electronic and optical properties and identify materials factors that limit the performance of III-As core-shell nanowires as infrared light emitting diodes and lasers. Single nanowire Raman, photoluminescence, and electrical measurements are used to spatially map strain, carrier concentrations and lifetimes, and the band offsets that establish confinement potentials.