Collaborative Research: Carrier dispersion and Nontrivial Topological Phases in Ultra-Low Bandgap Metamorphic InAsSb Ordered Alloys

适合于红外光电器件发展的半导体材料多年来一直受到物理学家和工程师的关注。变质分子束外延是一种新的材料开发技术，可以在很宽的原子浓度范围内精确控制其成分（铟、砷、铝和锑），从而生产高质量的化合物。这种能力允许对重要的窄带半导体的"量子"特性进行深入研究，这些窄带半导体受到材料缺陷的保护。这些性质可能对包括量子计算机在内的各种设备的性能具有深远的影响。在这个项目中，来自斯托尼布鲁克大学和格鲁吉亚理工学院的跨学科研究小组计划使用新材料来实验演示量子物理学的有趣特征。这些努力联合收割机结合了新材料的开发和通过各种先进的实验技术对其物理性质和能谱的研究。该项目还为物理学、材料科学和工程学研究生提供协同培训，为本科生创造研究机会。K-12教育部分旨在培养使用新材料和新技术来改善器件性能而不影响人类生活质量的早期意识。本项目是进行具有可控纳米级有序性的高质量砷化锑化铟（InAsSb）合金的外延生长，并研究这些材料中新的拓扑非平凡相的表现。材料生长是基于最近开发的虚拟衬底的方法，解除了衬底晶格常数的约束。通过改变晶格常数、应变、合金成分和成分调制周期，可以将InAsSb有序合金的物理性质控制到异常的程度。有了这些新材料，研究小组打算回答以下基本问题。(1)在具有纳米级有序性和可调带隙的InAsSb合金中，可以实现和观察到非平凡的拓扑相吗？(2)InAsSb有序合金能成为Majorana零模演示的新平台吗？这些主题是非常重要的基础和技术的兴趣，特别是对拓扑量子计算的固态实现。该项目的技术方法包括能带结构计算，先进的外延生长和尖端的表征方法。后者的特点是透射电子显微镜，高分辨率X射线衍射，倒易空间映射，红外光谱在高磁场，和角度分辨光电子能谱。参与该项目的研究生和本科生有独特的机会掌握这些方法，并参与材料开发过程的各个阶段。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Semiconductors suitable for the development of infrared opto-electronic devices attract attention of physicists and engineers for many years. Metamorphic molecular beam epitaxy, a novel technology for material development, produces high quality compounds with precise control of their composition (indium, arsenic, aluminum and antimony) over a wide range of atomic concentrations. This ability allows deep studies of the "quantum" properties of important narrow-band semiconductors that are protected against material imperfections. These properties may have profound implication for the performance of a variety of devices including quantum computers. In this project the interdisciplinary research team from Stony Brook University and Georgia Institute of Technology plans to use novel materials for experimental demonstration of intriguing features of quantum physics. The efforts combine development of new materials and study of their physical properties and energy spectra by a variety of advanced experimental techniques. The project also provides for synergetic training of graduate students in physics, material science, and engineering, creating research opportunities for undergraduate students. The K-12 education component aims at cultivating an early-stage awareness of using new materials and technologies to improve the device performance without compromising the quality of human life.This project is to carry out epitaxial growth of high-quality indium arsenide antimonide (InAsSb) alloys with controllable nanoscale ordering and to investigate the manifestations of the new topologically nontrivial phases in these materials. The material growth is based on a recently developed virtual substrate approach, which lifts the constraint from the substrate lattice constant. The physical properties of the InAsSb ordered alloys can then be controlled to an exceptional degree, via varying the lattice constant, the strain, the alloy composition, and the composition modulation period. With these new materials, the research team intends to answer the following fundamental questions. (1) Can nontrivial topological phases be realized and observed in metamorphic InAsSb alloys with nanoscale ordering and tunable bandgap? (2) Can the InAsSb ordered alloys be a new platform for demonstration of Majorana zero mode? These topics are of great fundamental and technological interest, particularly for the solid-state realization of topological quantum computing. The technical approaches of the project include band structure calculation, advanced epitaxial growth, and cutting-edge characterization methods. The latter features transmission electron microscopy, high-resolution x-ray diffraction, reciprocal space mapping, infrared spectroscopy in high magnetic fields, and angle-resolved photoemission spectroscopy. Graduate and undergraduate students participating in the project have unique opportunities to master these methods and engage in all stages of the material development process.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.