MRI: Development of a Localized Field Emission Scanning Electron Microscope and Secondary Electron Spin Polarization Analysis System

MRI：局域场发射扫描电子显微镜和二次电子自旋极化分析系统的开发

• 批准号: 1531997
• 负责人: Taryl Kirk
• 金额: $ 99.44万
• 依托单位: The College of New Jersey
• 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: 2015-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1531997&HistoricalAwards=false
• 关键词: MRI; Development; Localized; Field; Emission

The Major Research Instrumentation award supports the development of a novel cost-efficient electron microscope capable of imaging the top-most layers of surfaces with high spatial resolution at the College of New Jersey. The scope of the project is to combine the fundamental concepts of scanning electron (SEM) and scanning probe microscopies (SPM) into a single instrument called "Near Field Emission Scanning Electron Microscopy" (NFESEM). The use of low energy electrons NFESEM will have an impact over many areas including biological, medical, data storage, computing and renewable energy. The device will immediately provide an alternative, high resolution surface imaging device to researchers in both New Jersey and Eastern Pennsylvania. The results from this project will be incorporated in course curricula at The College of New Jersey. Undergraduate students involved in the project will be trained and acquire expertise in these techniques. The instrumentation will help underpin forthcoming technological developments especially in the area of ultra large scale integrated circuits and spintronics. Furthermore, the collaboration scheme which includes early career and well-established scientists and engineers will impact research on superconductivity, low energy electron spectroscopy, nano-device characterization, nanoparticle enabled drug delivery and more. Involvement of industrial partners will enhance the training and transfer of knowledge. The researchers will also use this as an opportunity to introduce underrepresented middle school and high school students from Trenton to basic microscopy and its applications.NFESEM will provide a means of overcoming the limitations of conventional scanning electron microscopes (SEM) and opens the possibility to use lower primary beam energies ( 100 eV). In essence, NFESEM is an intermediate technique in which electrons are emitted from a needle tip via field electron emission, and then impinge on and interact with the sample. As a result, electrons are ejected from the sample surface and detected and an electron spin detector will be incorporated into the system for polarization analysis of ejected secondary electrons. The NFESEM coupled with a spin polarimetry will enable SEM with polarization analysis capable of nanometer magnetic imaging, in particular low dimensional magnetic systems. The microscope will be equipped with a cryogen-free electro-magnet that is constructed to magnetize the sample of interest with a magnetic field up to 3,000 Gauss. The design and the control unit added to the scanning probe microscope will allow for high speed imaging, which is essential to simulate the imaging capabilities of standard scanning electron microscopes. The unique operating mode of the microscope, coupled with the polarimeter, generates three characteristic signals: 1) field emission current; 2) variations in the backscattered and secondary electron signal; and 3) a three dimensional surface spin asymmetry. This ensemble will enable nanometric imaging of magnetic materials; in particular, low dimensional magnetic systems. The NFESEMPA will be the first of its kind, and the proposed research team will be able to determine the advantages and/or disadvantages of using lensless scanning electron microscopy, c.f. contemporary SEMPA. Accordingly, this project will present an alternative method to generate a fine electron beam for high resolution imaging of atomically "smooth" surfaces.

主要研究仪器奖支持开发一种新型的具有成本效益的电子显微镜，能够在新泽西学院以高空间分辨率对表面的最顶层进行成像。该项目的范围是将扫描电子显微镜（SEM）和扫描探针显微镜（SPM）的基本概念联合收割机结合到一台称为“近场发射扫描电子显微镜”（NFESEM）的仪器中。 低能量电子的使用NFESEM将对许多领域产生影响，包括生物，医疗，数据存储，计算和可再生能源。该设备将立即为新泽西和宾夕法尼亚州东部的研究人员提供替代的高分辨率表面成像设备。该项目的成果将纳入新泽西学院的课程。参与该项目的本科生将接受培训，并获得这些技术的专业知识。该仪器将有助于支持未来的技术发展，特别是在超大规模集成电路和自旋电子学领域。此外，包括早期职业和成熟的科学家和工程师在内的合作计划将影响超导性，低能电子光谱学，纳米器件表征，纳米粒子使能药物输送等方面的研究。工业伙伴的参与将加强培训和知识转让。研究人员还将利用这一机会向来自特伦顿的代表性不足的初中和高中学生介绍基本显微镜及其应用。NFESEM将提供一种克服传统扫描电子显微镜（SEM）局限性的方法，并开辟使用较低初级束能量（100 eV）的可能性。本质上，NFESEM是一种中间技术，其中电子通过场电子发射从针尖发射，然后撞击样品并与样品相互作用。结果，电子从样品表面射出并被检测，并且电子自旋检测器将被并入系统中以用于射出的二次电子的极化分析。NFESEM与自旋极化法相结合将使具有极化分析能力的SEM能够进行纳米磁性成像，特别是低维磁性系统。该显微镜将配备一个无冷冻剂的电磁铁，其构造可使感兴趣的样品在高达3，000高斯的磁场下磁化。设计和控制单元添加到扫描探针显微镜将允许高速成像，这是必不可少的模拟标准扫描电子显微镜的成像能力。显微镜的独特操作模式，加上偏振计，产生三个特征信号：1）场发射电流; 2）背散射和二次电子信号的变化;和3）三维表面自旋不对称性。该集成将使磁性材料的纳米成像，特别是低维磁性系统。NFESEMPA将是同类中的第一个，拟议的研究小组将能够确定使用无透镜扫描电子显微镜的优点和/或缺点。现代SEMPA因此，这个项目将提出一种替代方法来产生一个精细的电子束，用于原子“光滑”表面的高分辨率成像。