Graphene Thermoelectric THz Direct and Heterodyne Detectors

石墨烯热电太赫兹直接和外差探测器

• 批准号: 1509599
• 负责人: Jun Yan
• 金额: $ 36万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509599&HistoricalAwards=false
• 关键词: Graphene; Thermoelectric; THz; Direct; Heterodyne

Detection of terahertz or THz radiation, the electromagnetic waves with frequencies in-between that of microwaves and infrared light, is useful for a wide range of applications, including investigating the formation and evolution of stars and galaxies in the universe, analyzing the thickness of coatings on pills and tablets in the pharmaceutical industry, distinguishing cancer cells from healthy tissues, spotting manufacturing flaws for non-destructive quality-control analysis, identifying concealed objects under clothing, and sniffing out explosives and illegal drugs remotely. A long-standing objective of THz technology research has been to develop a multi-pixel THz "camera" that can produce images of the THz radiation from an object, similar to the commonly-used digital cameras that take pictures with visible light. Because of the limited sensitivity and speed for typical room temperature devices, THz imaging presently requires the use of a high power, coherent, THz illumination source. Meticulously engineered THz detectors can reach high sensitivity and fast speed. However such devices typically need to be cooled down to cryogenic temperatures. Here graphene, a single atomic sheet of carbon atoms, will be used to make compact and high performance THz detectors operating at room temperature. Specifically graphene will be processed into a thermocouple that can rapidly and efficiently sense the heating effects due to THz radiation absorption. Fully optimized devices from the project are expected to reach a performance equivalent to existing systems that have to be cooled down with liquid helium, paving way for developing a compact room temperature THz camera that can record thermal images of the environment without the need for an intense THz light source. This research project will provide a unique inter-disciplinary scientific education and training program in two dimensional materials, nano science, technology and engineering, optics, THz instrumentation and condensed matter physics to graduate, undergraduate and high school students from diverse socio-economic backgrounds and under-represented communities.Recent intense electrical and optical studies of graphene have pushed the material to the forefront of THz research due to the atomically thin crystal's high mobility, weak electron-phonon coupling, tunable broadband optical response and minute specific heat. The proposed research seeks to take advantage of these unique properties and fabricate high quality graphene-boron nitride atomic stacks to detect THz radiation through a thermoelectric mechanism: THz radiation heats up electrons in graphene while keeping the lattice in thermal equilibrium with the environment; the diffusion of hot electrons creates a temperature gradient which, in a device with broken mirror symmetry, generates a thermoelectric voltage signal. This detection mechanism can effectively circumvent performance roll off at high THz frequencies, commonly encountered in gallium arsenide Schottky barrier diode and semiconductor plasmon detectors, and provide very fast response due to graphene?s small electron heat capacity. The THz detectors will be coupled to the incoming radiation through an integrated circuit antenna and a silicon lens. The project will develop: 1. graphene thermoelectric direct detectors with high responsivity, fast speed and low noise equivalent power; 2. graphene thermoelectric heterodyne detectors reaching high sensitivity with low local oscillator power requirement and room temperature operation. The potential for employing the heterodyne detectors in future THz array imagers will be evaluated. In addition to potential applications, the results are expected to provide key information to elucidate the underlying mechanism of the relevant physical processes, including the speed of the thermoelectric process, generation and relaxation of hot electrons, as well as the impacts of the charge density and impedance profile on the thermoelectric voltage.

检测Terahertz或Thz辐射，在微波和红外光之间具有频率的电磁波，可用于广泛的应用，包括研究宇宙中恒星和星系的形成和演化质量控制分析，识别服装下隐藏的物体，以及远程嗅出炸药和非法药物。 THZ技术研究的一个长期目标是开发一个多像素THZ“相机”，该“相机”可以从物体中产生THZ辐射的图像，类似于使用可见光的图片拍摄图片的常用数码摄像机。由于对典型室温设备的灵敏度和速度有限，因此THZ成像目前需要使用高功率，相干，THZ照明源。精心设计的THZ检测器可以达到高灵敏度和快速速度。但是，这些设备通常需要冷却到低温温度。这里的石墨烯是单个原子片碳原子，将用于使在室温下运行的紧凑和高性能THZ探测器。特异性石墨烯将被处理成热电偶，该热电偶可以快速有效地感知由于吸收THZ辐射引起的加热效应。预计该项目的完全优化的设备将达到相当于现有系统的性能，这些性能必须用液体氦气冷却，铺路方法可以开发紧凑的室温THZ摄像头，该摄像头可以记录环境的热图像，而无需强烈的THZ光源。该研究项目将提供独特的跨学科科学教育和培训计划，以二维材料，纳米科学，技术，技术和工程，光学，仪器，THZ仪器和凝结物理学，以毕业，本科和高中生的毕业，本科和高中生，来自多样化的社会经济背景和不足的社区，以及对绘制的强度和优先研究的幅度，这些幅度是绘制的。晶体的高迁移率，弱电子耦合，可调宽带光学响应和微小特异性热量。拟议的研究旨在利用这些独特的特性，并制造高质量的石墨烯氮化原子堆栈，以通过热电机制检测THZ辐射：THZ辐射在石墨烯中加热电子，同时将晶格保持在与环境的热平衡状态；热电子的扩散产生了温度梯度，该温度梯度在具有破碎的镜子对称性的设备中产生热电电压信号。这种检测机制可以有效地绕过高THZ频率的性能，通常在Arsenide Schottky屏障二极管和半导体等离子体探测器中遇到，并且由于石墨烯的小电子热容量而产生的响应非常快。 THZ检测器将通过集成的电路天线和硅透镜耦合到传入的辐射。该项目将开发：1。石墨烯热电直接检测器，具有高响应性，快速速度和低噪声等效功率； 2。石墨烯热电杂差检测器，达到高灵敏度，局部振荡器功率要求低和室温运行。将评估在未来的THZ阵列成像中使用杂化检测器的潜力。除了潜在的应用外，结果还有望提供关键信息，以阐明相关物理过程的潜在机制，包括热电过程的速度，热电子的产生和放松以及电荷密度和对热电压的损伤的影响。