Graphene on Nanoscale Gratings for Terahertz Light Emission

该项目由材料研究部（DMR）的电子和光子材料项目（EPM）和电气、通信和网络系统部（ECCS）的电子、光子学和磁性器件项目（EPMD）共同资助。技术描述：该项目的目标是在纳米级光栅上开发高质量的石墨烯样品，用于基于新型辐射机制产生太赫兹（THz）光，到目前为止，该机制一直是真空系统中高能电子束的主要领域。具体来说，正在研究的机制包括一个全新的类似回旋加速器的发射过程，其中角运动是通过几何约束而不是通过外部磁场的应用来获得的，以及史密斯-珀塞尔效应。项目活动包括纳米光刻技术，用于制造高正弦纳米尺度光栅，通过剥离和高真空化学气相沉积合成石墨烯，石墨烯转移，以及通过门控电学研究、拉曼光谱和太赫兹辐射测量来表征样品。石墨烯的独特性质（包括其线性能量色散，高电子速度和迁移率以及二维性质）非常适合正在研究的辐射机制。同时，通过对这些现象的论证和研究，可以揭示有关底层材料物理的关键信息。非技术描述：石墨烯是一种二维晶体，由单层碳原子排列成蜂窝状晶格。凭借几种独特的电子、光学和机械性能，它代表了一个有前途的材料平台，使电子和光子技术的持续发展朝着不断提高的性能、小型化和功能发展，远远超出了传统半导体的基本限制。该项目研究了利用这些特性来开发紧凑固态系统中太赫兹光发射的新范例。因此，它可能为新型太赫兹器件（包括可能能够在室温下工作的太赫兹激光器，与所有现有的基于半导体的解决方案不同）开辟道路，以满足安全检查、医疗诊断和制造质量控制等广泛新兴应用的需要。在这些活动的过程中，通过对学生进行材料科学和纳米技术几个领域的培训来促进教育，除了博士候选人外，还特别强调本科生和高中实习生的参与。一个相关的目标是基于研究方法和成果开发实验模块，以增强波士顿大学纳米技术本科课程的实验组成部分，并由参与波士顿大学激励大使计划的本科生在当地高中（包括有大量少数民族人口的学院）进行演示。

This project is jointly funded by the Electronic and Photonic Materials Program (EPM) in the Division of Materials Research (DMR) and the Electronics, Photonics, and Magnetic Devices Program (EPMD) in the Division of Electrical, Communications and Cyber Systems (ECCS). Technical Description: The goal of this project is to develop high-quality graphene samples on nanoscale gratings for the generation of terahertz (THz) light based on novel radiation mechanisms that so far have been the primary domain of high-energy electron beams in vacuum-based systems. Specifically, the mechanisms under study include a radically new cyclotron-like emission process, where angular motion is obtained via geometrical constraints rather than through the application of an external magnetic field, and the Smith-Purcell effect. The project activities involve a combination of nanolithography for the fabrication of highly sinusoidal nanoscale gratings, graphene synthesis via exfoliation and high-vacuum chemical vapor deposition, graphene transfer, and sample characterization via gated electrical studies, Raman spectroscopy, and THz-radiation measurements. The distinctive properties of graphene (including its linear energy dispersion, high electron velocity and mobility, and two-dimensional nature) are uniquely suited to the radiation mechanisms under study. At the same time, critical information about the underlying materials physics can be unveiled through the demonstration and investigation of these phenomena.Non-technical Description: Graphene is a two-dimensional crystal consisting of a single layer of carbon atoms arranged in a honeycomb lattice. By virtue of several unique electronic, optical, and mechanical properties, it represents a promising materials platform to enable the continued evolution of electronic and photonic technologies towards ever increasing performance, miniaturization, and functionalities, well beyond the fundamental limits of traditional semiconductors. This project investigates the use of these properties to develop a new paradigm for THz light emission in compact solid-state systems. As a result, it may open the way for a new class of THz devices (including THz lasers potentially capable of room-temperature operation, unlike all existing semiconductor-based solutions), as needed for a wide range of emerging applications in security screening, medical diagnostics, and manufacturing quality control. In the course of these activities, education is promoted through the training of students in several areas of materials science and nanotechnology, with a strong emphasis on the involvement of undergraduates and high-school interns in addition to Ph.D. candidates. A related goal is the development of experimental modules based on the research methods and outcomes, to enhance the laboratory component of an undergraduate course on nanotechnology at Boston University (BU), and for demonstrations at local high schools (including institutes with large minority populations) by undergraduates engaged in BU Inspiration-Ambassadors program.