Total Tomography of Nonplanar Heterostructures for Quantum Information Processing

非技术描述：半导体材料，特别是由第III族和第V族元素组成的合金，被广泛用于以电子方式处理信息并将电流转换为光的设备，从而实现被认为在现代社会必不可少的快速有效的通信。不同的III-V半导体可以在纳米级的异质结构中结合在一起，通过利用量子力学制造具有以全新方式处理信息的潜在设备。该项目正在使用先进的沉积和表征方法，目标是发展对半导体合金如何形成具有超导接触的纳米级导线以产生新的信息存储、计算和通信模式的基本了解。此外，该项目旨在保持美国在新信息技术和未来劳动力方面的竞争力。为此，研究生在西北大学和国家实验室接受与量子技术相关的材料系统的尖端三维表征方法培训。技术描述：在网络拓扑中生长的衬底模板纳米线异质结构是涉及Majorana准粒子的量子计算方案的候选方案。窄带隙III-As/Sb半导体中的能带偏移可以为电子产生所需的限制势，但异质结构必须以适当的尺寸、几何形状和精度生长，以便能够与金属和超导接触进行所需的耦合。本项目的目标是在三维空间关联III-As/Sb异质结的组成、应变和电子结构，以了解组成和应变如何影响纳米结构的生长和电子性质，特别是自由载流子在具有强自旋轨道耦合的准一维能带中的空间分布。我们还研究了这些异质结中量子化发射体的光学性质。利用原子探针层析成像技术测量了III-As/Sb纳米线异质结的三维纳米组成。基于这些成分数据，用弛豫物理结构的有限元模型模拟和解释了同步加速器基单纳米线的X射线衍射和成像。结合应变和成分数据，包括原子探针断层扫描测量的掺杂分布，被用来建立纳米结构生长和电子性质的模型。相关的单纳米线阴极发光提供了带隙和有源载流子浓度的空间分辨测量，相关的透射式电子显微镜测量分别限制了原子探针和X射线成分和应变的重建。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical description: Semiconducting materials, particularly alloys composed of group III and group V elements, are extensively used in devices that process information electronically and convert electrical currents to light, enabling fast and efficient communication considered essential in modern society. Different III-V semiconductors can be combined in heterostructures at the nanometer scale to make devices with the potential to process information in entirely new ways by exploiting quantum mechanics. This project is using advanced deposition and characterization methods with the goal to develop fundamental understanding of how semiconducting alloys can be formed into nanoscale wires with superconducting contacts to produce new modes of information storage, computation, and communication. Furthermore, this project aims to maintain the competitiveness of the United States in new information technologies and the future workforce. Towards that end, graduate students are trained in cutting-edge three-dimensional characterization methods at Northwestern University and in national laboratories on materials systems relevant to quantum technologies.Technical description: Substrate-templated nanowire heterostructures grown in network topologies are candidates for quantum computing schemes involving Majorana quasiparticles. Band-offsets in narrow band-gap III-As/Sb semiconductors can produce the required confinement potentials for electrons, but heterostructures must be grown with the appropriate size, geometry, and precision to enable the desired coupling to metal and superconducting contacts. The goal of this project is to correlate the composition, strain, and electronic structure of III-As/Sb heterostructures in three dimensions to understand how composition and strain influence nanostructure growth and electronic properties, particularly the spatial distribution of free carriers in quasi-one-dimensional bands with strong spin-orbit coupling. Optical properties of quantized emitters in these heterostructures are also investigated. Atom probe tomography is used to measure three-dimensional nanoscale composition fields of III-As/Sb nanowire heterostructures. Based on these composition data, finite element models of relaxed physical structure are used to simulate and interpret synchrotron-based single nanowire x-ray diffraction and imaging. The combined strain and composition data, including dopant distributions measured by atom probe tomography, are used to develop models of nanostructure growth and electronic properties. Correlated single nanowire cathodoluminesence provides spatially resolved measurements of band-gap and active carrier concentrations, and correlated transmission electron microscopy measurements constrains atom probe and x-ray reconstructions of composition and strain, respectively.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.