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Our objective is to provide comprehensive descriptions of the
Our approach is to apply state-of-the-art synchrotron measurement capabilities at the National Synchrotron Light Source (NSLS) and the Advanced Photon Source (APS) to generate structure data that cannot be measured by other methods. We collaborate with leading researchers from industry, other government agencies, and universities to address the nation’s most pressing measurement needs. The methods that we employ include: (1) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy; (2) extended X-ray absorption fine structure (EXAFS) spectroscopy; (3) variable kinetic energy X-ray photoelectron spectroscopy (VKEXPS); (4) grazing incidence X-ray diffraction; and (5) small angle X-ray scattering and reflectivity. Methods (1) – (3) are available at the NIST beamlines at the NSLS, while methods (4) and (5) are located at the APS.
Impact and Customers:
One of the semiconductor industry’s “Grand Challenges” is to develop an alternative to the SiO2 gate dielectric. Integrated circuits exhibiting greater speed and lower power consumption are no longer attainable with ultrathin (= 2 nm) SiO2 gate dielectrics due to their high direct tunneling leakage currents. Our collaboration with SEMATECH has led to extensive evaluation of conductive metal gate electrodes and thin film metal oxides as promising high dielectric constant (highk) replacement insulator materials. We have measured core level binding energy spectra as a function of annealing temperature for AlO/SiO/Si gate stacks. An AlO/SiO interface effect is detected by the shift of the oxidized Si4+ 1s core peak to higher binding energy with increased annealing temperature, indicating interfacial modification of the Si sub-stochiometric chemical oxide.
Si 1s core-level spectra from an Al2O3/SiO2/Si gate stack as a function of annealing temperature.
GISAXS data for ALD HfO2 film.
Changes in Co-O bond length (EXAFS) and lattice constant (XRD).
natural sources of U ground water contamination. Although nature provides only a small number of examples of UV minerals, exotic UV species can form in the unusual geochemical environments existing in nuclear fuel storage facilities and in the vadose and ground water regions contaminated by leaking storage facilities. The synthesis, crystal structure and spectroscopic characterization of [UV(HO)(UVIO)O(OH)](H2O)4, a novel, stable UV/UVI oxide material not requiring the incorporation of carbonate, silicate, or organic ligands, were recently reported. EXAFS on a powdered form of this mineral was measured at beamline X23A2, verifying the mixed-valence of the U and the structure determined by single crystal x-ray diffraction.
EXAFS of the mixed valence uranium mineral
Start Date:October 24, 2008
Lead Organizational Unit:mml
Project Summary (PDF)