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

非技术性：原子探测器是一种显微镜，可以对材料中的单个原子进行三维渲染。通过能够想象原子是如何聚集在一起的，科学家们能够理解并因此设计出改进能量转换、导电或磁数据存储的材料。阿拉巴马大学(UA)在这些领域和其他需要这种原子级成像的领域有关键的研究计划。UA的研究人员正在研究一种涂层，可以改善用于先进发电机和飞机发动机的涡轮叶片的生命周期。此外，学院研究人员还赞助了开发燃料电池材料的努力。UA拥有一个由政府和工业赞助的磁记录研究中心。该中心在开发高存储密度、高灵敏度传感器和更快的逻辑器件(如晶体管)材料方面开展了积极的计划。用于这些新技术的这些材料大多使用氧化物材料，这种材料的导电性很差。在历史上，原子探测器要求材料是导电的(金属)。激光脉冲技术的最新进展使原子探测器能够成像半导体和绝缘体等劣质电导体。UA的原子探测器所要求的激光附件随后将扩大可以在这些战略计划中表征的材料的范围。激光附件提供了一种独特的能力，可以促进与几个地区性机构的合作，包括历史上的黑人学院和大学。此外，它还为加州大学材料科学专业的学生招生提供服务。技术：在三维微结构中定位单个原子的能力已经成为材料表征的基本需求，以将实验观察与原子尺度建模联系起来。原子探测器仪器场从感兴趣的样品中蒸发原子，这些原子被收集在位置敏感的质谱型探测器上。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质的体积重建渲染。在历史上，原子探针样品需要导电，才能使高压脉冲传播到样品的顶端，以便场蒸发表面原子。随着激光的商业化应用，现在可以在蒸发过程中对劣质导体(陶瓷和半导体)进行热辅助。阿拉巴马大学(UA)有几个利用介电材料的研究项目。通过原子探针显微镜对这些材料进行表征的能力将极大地推动这些计划。例如，UA在用于下一代栅值的高k介电HfO2方面的努力表明，氮掺杂可以显著减少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，潜在的理解受到了阻碍。UA在巨磁电阻传感器和隧道磁阻器件的自旋电子研究方面一直处于领先地位。原子探测器能够表征这些薄膜堆栈中的埋藏氧化物界面，这将进一步促进我们在测量属性和建模之间的联系。激光还将允许我们现场蒸发脆性金属间化合物，如FePT，它们是超高磁存储介质的候选者。最后，UA有积极的基于能源的研究计划。激光附着在原子探针上将使我们能够在其催化载体结构(如石墨和氧化铝)上表征PtRu合金。同样，激光将提高表征用于发电涡轮叶片的热保护涂层中氧化皮形成的能力。UA的支持基础设施和人员配备得非常好，可以开发原子探测器样品，并将激光的使用推广到各种材料上。能力的增强将保持普遍定期审议作为国家分析机构的地位，并继续促进我们现有的与HBCU机构的外联研究活动。

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.