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.
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.
