Collaborative Research: Tailoring Terahertz Emission in Ultrafast Multi-Functional Devices using Reduced-Dimensional Hybrid Metal Perovskites

非技术：太赫兹技术对未来的计算和通信有着巨大的希望。使用轻质、低成本和坚固材料的节能和小型化太赫兹源是一个长期追求的目标。然而，很少有材料具有实现工作装置所需的属性。降维金属卤化物钙钛矿是一种新型半导体材料，具有广阔的应用前景。它们可以廉价地合成和溶液加工，具有吸引人的电子特性，并且可以容忍缺陷。这些特性引起了人们对太阳能电池和柔性显示器应用的极大兴趣。钙钛矿也有望成为高性能太赫兹源。值得注意的是，这些特性可以通过利用设备中电子的基本特性的自旋电子学（自旋电子学）来控制。这使得钙钛矿与磁性材料的界面成为可能，从而实现自旋电子太赫兹发射器。该项目将导致低成本和节能太赫兹器件具有互补的磁，光学和电子功能。pi将通过将研究与教育结合起来，教育研究生和本科生，包括那些来自代表性不足群体的学生。已建立和发展的外展计划将用于让K-12学生参与该项目。技术：本项目重点研究RD-HMH/铁磁体异质结构中宽带太赫兹发射的自旋电子控制的实现。该研究包括三个研究重点：(1)利用低成本自旋镀膜方法制备的降维杂化金属卤化物（RD-HMH）多晶薄膜，利用自旋的快速弛豫（类似于开关）和RD-HMHs中重金属元素的有效自旋-电荷互转换，展示了概念验证自旋电子杂化太赫兹发射器。对RD-HMH/铁磁体异质结构中超快产生太赫兹辐射的彻底的、基本的物理理解将被揭开。(2)通过工程化RD-HMH单晶对太赫兹辐射进行裁剪。基于单晶片的太赫兹发射器将被设计和优化，具有可调谐的带宽以及高质量（Q-）因子，作为多晶薄膜发射器的补充。(3)利用器件构建块通过多种化学合成路线优化太赫兹辐射。具有可调谐量子阱效应的高质量合成RD-HMH候选材料已经准备好被制造成高效的太赫兹发射器，允许自旋电子和磁控制太赫兹的产生，可以潜在地用于利用太赫兹波发射和吸收的逻辑应用。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。

Nontechnical: Terahertz technologies hold great promise for future computing and communications. Energy-efficient and miniaturized THz sources using light-weight, low-cost, and robust materials are a long sought goal. Few materials, however, possess the attributes needed to realize working devices. Metal halide perovskites with reduced dimensionality are a new class of semiconductors with great promise for such applications. They can be inexpensively synthesized and solution processed, have attractive electronic properties, and tolerate defects. These properties have led to great interest for applications in solar cells and flexible displays. Perovskites also show promise as high performance THz sources. Remarkably, these properties can be controlled via spin electronics (spintronics) that exploit the fundamental properties of electrons in devices. This makes it possible to interface perovskites with magnetic materials, enabling spintronic THz emitters. This project will lead to low-cost and energy-efficient THz devices with complementary magnetic, optical and electronic functions. The PIs will educate graduate and undergraduate students, including those from underrepresented groups, by integrating research with education. Established and developing outreach programs will be used to involve K-12 students with the project.Technical:This project focuses on the realization of a spintronic control of the broadband THz emission in RD-HMH/Ferromagnet heterostructures. The research consists of three research thrusts: (1) Demonstrate the proof-of-concept spintronic hybrid THz emitter using reduced dimensional-hybrid metal halide (RD-HMH) polycrystalline thin films prepared by a low-cost spin-coating approach, taking advantage of the fast relaxation of spin (akin to a switch) and efficient spin-to-charge interconversion thanks to the heavy metal elements in RD-HMHs. A thorough, fundamental physical understanding of the ultrafast generation of THz emission in RD-HMH/Ferromagnet heterostructures will be unraveled. (2) Tailor the THz emission via engineering RD-HMH single crystals. Wafer-scale single crystals-based THz emitters will be designed and optimized with tunable bandwidth as well as high quality (Q-) factors, in complement to that of polycrystalline-film emitters. (3) Optimize the THz emission via versatile chemical synthetic routes using device building blocks. The available pool of high-quality synthesized RD-HMH candidates with tunable quantum-well effects are ready to be fabricated into efficient THz emitters, allowing the spintronic and magnetic control of THz generation that can be potentially used for logic applications utilizing THz-wave emission and absorption.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.