MRI: Acquisition of a Fast-Pulse-Laser for a Local Electrode Atom Probe

MRI：采集用于局部电极原子探针的快脉冲激光

• 批准号: 0722631
• 负责人: Gregory Thompson
• 金额: $ 50万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0722631&HistoricalAwards=false
• 关键词: MRI; Acquisition; Fast; Pulse; Laser

Non-technical: The atom probe is a microscope that allows three dimensional rendering of individual atoms in a material. By being able to image how atoms cluster together, scientists are able to understand and thereby engineer materials for improved energy conversion, electrical conduction or magnetic data storage. The University of Alabama (UA) has key research programs in these and other areas that require this type of atomic level imaging. UA researchers are working on coatings that can improve the life cycle for turbine blades used in advanced power generators and aircraft engines. Additionally, faculty researchers have sponsored efforts in developing materials for fuel cells. UA houses a government and industrial sponsored magnetic recording research center. This center has active programs in developing materials for high storage densities, high sensitivity sensors and faster logic devices, such as transistors. Most of these materials for these new technologies use oxide-based materials, which are poor electrical conductors. Historically, atom probes required materials that were electrically conductive (metals). Recent advances in laser pulsing has allowed atom probes to image poor electrical conductors, such as semiconductors and insulators. The requested laser attachment to UA's atom probe will subsequently expand the range of materials that can be characterized in these strategic programs. The laser attachment provides a unique capability in fostering collaboration with several regional institutions, including historically black colleges and universities. Additionally, it serves in recruitment of students into the materials science discipline at UA. Technical: The ability to pin-point an individual atom in a three-dimensional microstructure has become an essential need in materials characterization to link experimental observations to atomic scale modeling. The atom probe instrument field evaporates atoms from a specimen of interest which are collected on a position-sensitive, mass-spectrum detector. By reconstructing the trajectory path and impact position of each ion, a volumetric reconstructed rendering of the material is generated with near atomic precision for each individual atom. Historically, atom probe specimens needed to be conductive in order for the high voltage pulse to propagate to the apex of the specimen to field evaporate the surface atoms. The commercial advent of the laser now allows poor conductors (ceramics and semiconductors) to be thermally assisted in the evaporation process. The University of Alabama (UA) has several research programs that utilize dielectric materials. The ability to characterize these materials by atom probe microscopy would significantly advance these programs. For example, UA's efforts on high-k dielectric HfO2 for next-generation gate-values has shown that nitrogen-doping can significantly reduce intermixing between HfO2 and Si; however, an underlying understanding has been hampered by the inability to characterize subtle composition changes at the interface. UA has a track-record of being leaders in spintronic research for giant magnetoresistance sensors and tunneling magnetoresistance devices. The atom probe's ability to characterize buried oxide interfaces within these thin film stacks would further facilitate our linkage between measured properties and modeling. The laser would also allow us to field evaporate brittle intermetallics, like FePt, that are candidates for ultrahigh magnetic storage media. Finally, UA has active energy-based research programs. The laser attachment to our atom probe would allow us to characterize PtRu alloys on their catalytic support structures, such as graphite and alumina. Similarly, the laser will increase the capability to characterize oxide scale formation in thermal protective coatings used for power generation turbine blades. UA's supporting infrastructure and personnel is exceptionally well equipped to develop atom probe specimens and advance the usage of the laser to a wide range of materials. The increased capability will maintain UA as a national analytical facility and continue to foster our existing outreach research activities with HBCU institutions.

非技术性：原子探针是一种显微镜，可以对材料中的单个原子进行三维渲染。通过对原子如何聚集在一起的图像进​​行成像，科学家们能够理解并从而设计材料以改善能量转换、导电或磁性数据存储。阿拉巴马大学 (UA) 在这些领域和其他需要此类原子级成像的领域拥有重要的研究项目。 UA 研究人员正在研究可以改善先进发电机和飞机发动机中使用的涡轮叶片的生命周期的涂层。此外，教师研究人员还资助了燃料电池材料的开发工作。 UA 设有政府和工业资助的磁记录研究中心。该中心积极致力于开发高存储密度、高灵敏度传感器和更快的逻辑器件（例如晶体管）的材料。这些新技术的大部分材料都使用氧化物基材料，这些材料的电导体较差。从历史上看，原子探针需要导电材料（金属）。激光脉冲的最新进展使原子探针能够对半导体和绝缘体等不良电导体进行成像。 UA 原子探针所要求的激光附件将随后扩大这些战略计划中可表征的材料范围。激光附件提供了促进与多个地区机构（包括传统黑人学院和大学）合作的独特功能。此外，它还负责招募 UA 材料科学学科的学生。技术：在三维微观结构中精确定位单个原子的能力已成为材料表征中将实验观察与原子尺度建模联系起来的基本需求。原子探针仪器场从感兴趣的样品中蒸发原子，这些样品被收集在位置敏感的质谱检测器上。通过重建每个离子的轨迹路径和撞击位置，可以为每个单独的原子生成接近原子精度的材料体积重建渲染。从历史上看，原子探针样本需要导电，以便高压脉冲传播到样本的顶点以场蒸发表面原子。激光的商业化出现现在允许不良导体（陶瓷和半导体）在蒸发过程中得到热辅助。阿拉巴马大学 (UA) 有多个利用介电材料的研究项目。通过原子探针显微镜表征这些材料的能力将显着推进这些计划。例如，UA 在下一代栅极值高 k 电介质 HfO2 方面所做的努力表明，氮掺杂可以显着减少 HfO2 和 Si 之间的混合；然而，由于无法表征界面上细微的成分变化，阻碍了基本的理解。 UA 在巨磁阻传感器和隧道磁阻器件的自旋电子学研究方面拥有领先地位。原子探针能够表征这些薄膜叠层内的掩埋氧化物界面，这将进一步促进我们在测量的特性和建模之间建立联系。激光还使我们能够场蒸发脆性金属间化合物，例如 FePt，它们是超高磁存储介质的候选者。最后，阿布扎比大学拥有积极的能源研究项目。原子探针上的激光附件将使我们能够表征催化支撑结构上的 PtRu 合金，例如石墨和氧化铝。 同样，激光将提高表征用于发电涡轮叶片的热防护涂层中氧化皮形成的能力。 UA 的支持基础设施和人员装备精良，能够开发原子探针样本并将激光应用于各种材料。能力的增强将使 UA 保持作为国家分析设施的地位，并继续促进我们与 HBCU 机构现有的外展研究活动。