Imaging and controlling moire interactions in two-dimensional semiconductor heterostructures

二维（2D）材料是一个或几个原子的厚度。这些超薄材料展示了许多新的电子和其他效应，这些效应可以应用于新技术，如高速计算、太阳能收集和基于量子的技术。在过去的十年里，许多二维材料被发现，包括二维金属、半导体和磁铁。此外，这些二维材料可以堆叠在一起，以实现层与层之间相互作用所启用的特性。这些新特性使电子和光学器件成为可能，如晶体管、太阳能电池和激光器。本研究的重点是研究多层二维材料样品，利用这些层间相互作用来实现新的电子和光学特性。特别是，通过结合两种不同的二维半导体，研究小组将探索具有捕获电子的状态。这些被捕获的电子可以作为量子光源，这将有助于使量子通信设备免受网络攻击。这项研究符合美国国家科学基金会的量子飞跃大构想：通过开发有潜力实现这些新量子信息技术的材料系统，引领下一次量子革命。此外，该项目通过拟议的研究对研究生、本科生和高中生进行培训和指导，并通过鼓励亚利桑那州南部高中对STEM的兴趣，直接和间接地加强了STEM劳动力。二维材料在垂直异质结构中的堆叠，由于层间的晶格失配和相对取向导致了长波莫尔条纹的形成。这种莫尔条纹调制了异质结构的电子和光学性质，导致电子在一层和空穴在另一层的限制。这些受限的间接激子被认为是量子信息科学的资源，PI将研究如何利用二维半导体异质结构中moir<s:1>受限激子的新物理来实现具有新功能的量子器件。本项目主要研究由MoSe2和WSe2组成的二维半导体过渡金属二硫化物异质结构，形成ii型异质结。该项目的研究通过全面了解扭转角和层间相互作用在过渡金属二硫族化物异质结构中的作用，推进了量子材料物理学的知识。具体而言，本研究有三个目标：(1)利用扫描隧道显微镜成像MoSe2/WSe2异质结构中的莫尔激子势；(2)利用低温扫描近场光学显微镜直接测量空间调制的莫尔激子发射；(3)控制二维异质结构中的莫尔激子层间激子。最后，改变层间相互作用和势场，允许调整层间带隙，被捕获的莫尔莫尔激子的充电和莫尔莫尔势中的层间激子的凝聚。该奖项反映了美国国家科学基金会的法定使命，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。

Two-dimensional (2D) materials are a single or few atoms thick. These ultra-thin materials exhibit a host of new electronic and other effects that have applications to new technologies, such as high speed computing, solar energy harvesting, and quantum-based technologies. Over the past decade, many 2D materials have been discovered, including 2D metals, semiconductors, and magnets. Furthermore, these 2D materials can be stacked together to realize properties that are enabled by the interactions between layers. These new properties enable electronic and optical devices, like transistors, solar cells and lasers. This research is focused on investigating multi-layer 2D material samples that use these interlayer interactions to realize new electronic and optical properties. In particular, by combining two different 2D semiconductors, the research team will explore states with trapped electrons. These trapped electrons can act as quantum light sources, which would help enable quantum communication devices that are secure against cyber-attacks. This research aligns with the NSF Big Idea of the Quantum Leap: Leading the Next Quantum Revolution by developing material systems that have the potential to enable these new quantum information technologies. Furthermore, the project strengthens the STEM workforce both directly and indirectly by training and mentoring graduate, undergraduate, and high school students through the proposed research, and by encouraging interest in STEM at the high school level in southern Arizona.The stacking of 2D materials in a vertical heterostructure leads to the formation of a long wavelength moiré pattern due to the lattice mismatch and relative orientation between the layers. This moiré pattern modulates the electronic and optical properties of the heterostructure leading to the confinement of electrons in one layer and holes in the other layer. These confined indirect excitons are known to serve as resources for quantum information science, and the PI will investigate how the novel physics of moiré confined excitons in 2D semiconductor heterostructures can be exploited to realize quantum devices with new functionalities. This project is focused on 2D semiconducting transition metal dichalcogenide heterostructures consisting of MoSe2 and WSe2 which form a type-II heterojunction. The research in this project advances knowledge of quantum materials physics by developing a comprehensive understanding of the role of twist angle and interlayer interactions in transition metal dichalcogenide heterostructures. In particular, the research has three aims: (1) Image the moiré potential in MoSe2/WSe2 heterostructures using scanning tunneling microscopy, (2) Directly measure spatially modulated moiré exciton emission using low-temperature scanning near field optical microscopy and (3) Control moiré interlayer excitons in 2D heterostructures. Lastly, modifying the interaction between layers and the potential landscape, allows for the tuning of the interlayer bandgap, the charging of trapped moiré excitons and the condensation of interlayer excitons in the moiré potential.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.