Opportunity at National Institute of Standards and Technology NIST
Laser-Matter Interactions in Extreme Ultraviolet Atom Probe Tomography
Physical Measurement Laboratory, Applied Physics Division
Please note: This Agency only participates in the February and August reviews.
|Kristine A. Bertness
|Norman A. Sanford
Laser assisted atom probe tomography offers entirely new approaches for quantitative three-dimensional chemical analysis of complex nanostructures. However, conventional atom probe tomographs typically employ near-UV (355 nm) lasers. This is problematic because specimens of interest are often nanostructures variously composed of semiconductors, metals, oxides, nitrides--and sometimes even biological materials. Such multi-constituent assemblies exhibit significant nanoscale spatial variations in optical absorption efficiency and (thermal and electrical) transport properties. Because these factors can have strong spatially-dependent influences on field evaporation conditions, the quantitative interpretation of 3D elemental atomic reconstructions of (conventional) atom probe data can be quite difficult. It is therefore attractive to extend the laser excitation wavelength into the extreme ultraviolet (EUV)--spanning roughly 10-40 eV, and higher. EUV offers new "knobs to turn" in the study of laser-assisted field evaporation because nearly all materials of interest absorb rather uniformly in the EUV. Moreover, the (generally high) EUV photoionization cross sections exhibited across the periodic table, and with complex molecules, also suggest that field evaporation of elemental ions, rather than molecular ions, would be favored in an EVU-assisted atom probe tomograph. Our atom probe laboratory is equipped with both a conventional atom probe tomograph as well as a prototype EUV-modified atom probe tool. Furthmore, our collaborative laboratory structure provides critical in-house support including FIB, FESEM, aberration-corrected TEM, STEM, and a He-ion microscope. EDX, EELS, and thin-film XRD analysis capabilities are also available. The on-site facilities also include the availability of MBE growth systems for compound III-V semiconductors (arsenides and nitrides) and advanced nanofabrication and processing capabilities. We invite proposals aimed at both theoretical and experimental investigations of EUV atom probe tomography, novel approaches to conventional atom probe tomography, and new approaches to reconstruction data mining and analysis.
Extreme Ultraviolet; Laser-Matter Interactions; Atom Probe Tomography; Nanostructures; Quantitative Reconstruction Analysis; Field Evaporation
Open to U.S. citizens
Open to Postdoctoral applicants