Terahertz near-field microscopy of nanostructures and 2D materials

纳米结构和二维材料的太赫兹近场显微镜

• 批准号: 2436185
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2436185
• 关键词: Terahertz; near; field; microscopy; nanostructures

The terahertz frequency range sits between the microwave and mid-infrared regions of the electromagnetic spectrum, but has long resisted exploitation owing to difficulties in fabricating convenient sources and detectors; terahertz radiation is too high in frequency to be generated by the electronic techniques used in mobile telephones, but too low in frequency to be produced by the optical techniques exploited in, for example, CD player lasers. However, the last twenty years have witnessed a remarkable growth in the field owing to the development of innovative sources, detectors, and imaging systems-and in particular, the quantum cascade laser. These developments have enabled a wide range of imaging and spectroscopy studies in which the selective absorption or transmission of terahertz radiation has provided unique and fundamental information about the physical and chemical properties of materials in this relatively unexplored region of the spectrum. Recent commercial application of terahertz instrumentation is now finding application in the pharmaceutical and automotive industries, and in high-resolution fault isolation in semiconductor devices and 3D imaging of integrated circuits, inter alia.This PhD project will address this shortfall by combining two exciting technologies: scattering tip near-field imaging in an atomic force microscope (AFM), and self-mixing interferometry with terahertz quantum cascade lasers. Self-mixing interferometry is a technique that we have developed in which the emitting laser cavity itself is used as an exceptionally sensitive coherent self-detector of scattered/reflected radiation. Signals scattered from remote samples induce perturbations in the intra-laser electric field, and are manifest by measurable fluctuations in the laser voltage. We will combine this with a near-field imaging approach in which the incident terahertz radiation is focused locally on the sample by an AFM needle. By combining the nanometer-scale resolution of the AFM with the high sensitivity and compact footprint of the self-mixing detection technique, we will develop a terahertz nanoscale microscope and apply it to the investigation of a range of nanostructures and 2D materials in the terahertz range.

太赫兹频率范围位于电磁波谱的微波和中红外区域之间，但由于难以制造方便的源和检测器而长期以来一直抵制开发;太赫兹辐射的频率太高，无法通过移动的电话中使用的电子技术产生，但频率太低，无法通过例如CD播放器激光器中使用的光学技术产生。然而，在过去的二十年里，由于创新的光源、探测器和成像系统的发展，特别是量子级联激光器的发展，该领域取得了显着的增长。这些发展使得广泛的成像和光谱研究成为可能，其中太赫兹辐射的选择性吸收或透射提供了有关该相对未开发的光谱区域中材料物理和化学性质的独特且基本的信息。最近太赫兹仪器的商业应用现在正在制药和汽车行业中找到应用，以及在半导体器件中的高分辨率故障隔离和集成电路的3D成像等。这个博士项目将通过结合两种令人兴奋的技术来解决这一不足：在原子力显微镜（AFM）中的散射尖端近场成像，以及使用太赫兹量子级联激光器的自混合干涉测量。自混合干涉是一种我们已经开发的技术，其中发射激光腔本身被用作散射/反射辐射的异常灵敏的相干自检测器。从远程样品散射的信号在激光器内电场中引起扰动，并且通过激光器电压中的可测量波动来表现。我们将结合联合收割机这与近场成像的方法，其中入射太赫兹辐射是集中在本地的样品由AFM针。通过将AFM的纳米级分辨率与自混合检测技术的高灵敏度和紧凑的足迹相结合，我们将开发太赫兹纳米级显微镜，并将其应用于太赫兹范围内的一系列纳米结构和2D材料的研究。