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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Development Of The Gd(0001) Band Structure With Film Thickness, Dongqi Li, W. Hutchings, Peter A. Dowben, Rong-Tzong Wu, C. Hwang, M. Onellion, A.B. Andrews, J.L. Erskine
Development Of The Gd(0001) Band Structure With Film Thickness, Dongqi Li, W. Hutchings, Peter A. Dowben, Rong-Tzong Wu, C. Hwang, M. Onellion, A.B. Andrews, J.L. Erskine
Peter Dowben Publications
By growing gadolinium films on W(110), it has been possible to observe the development of the Gd(0001) band structure with increasing film thickness. The changes in the 5d bands as a result of exposure to oxygen or the development of the valence-band structure with increasing film thickness lead to changes in the 5p multiplet oscillator strengths. These changes are a result of the influence of the band structure upon the final-state effects that give rise to such multiplet structures. This study provides conclusive evidence that there is a 5d contribution to the shallow 5p multiplet photoemission …
Fabricating Magnetic Co-Ni-C Thin-Film Alloys By Organometallic Chemical Vapor Deposition, Yoon-Gi Kim, Dongjin Byun, C. Hutchings, Peter A. Dowben, H. Hejase, K. Schröder
Fabricating Magnetic Co-Ni-C Thin-Film Alloys By Organometallic Chemical Vapor Deposition, Yoon-Gi Kim, Dongjin Byun, C. Hutchings, Peter A. Dowben, H. Hejase, K. Schröder
Peter Dowben Publications
We have deposited CoxNiy-C films with a variety of compositions to verify dependence of the saturation magnetization on the composition. These experiments suggest that we can produce CoxNiy-C films with a variety of magnetic properties. The CoxNiy-C films were fabricated by ultraviolet decomposition of cobaltocene and nickelocene. We demonstrated that the photolytic decomposition of these metallocenes produces cyclopentadienyl (C5H5) species, consistent with recent studies of the energetics of the ligand metal bonds.
Probing The Metal-Nonmetal Transition In Thin Metal Overlayers Using Resonant Photoemission, Peter A. Dowben, D. Lagraffe, Dongqi Li, G. Vidali, L. Zhang, L. Dottl, M. Onellion
Probing The Metal-Nonmetal Transition In Thin Metal Overlayers Using Resonant Photoemission, Peter A. Dowben, D. Lagraffe, Dongqi Li, G. Vidali, L. Zhang, L. Dottl, M. Onellion
Peter Dowben Publications
We have studied one and two monolayers of barium on Ni(111) and of mercury on Cu(100). Using resonant photoemission, we have found core excited electrons become delocalized with increasing barium coverage. Similarly, upon formation of the mercury bilayer (as determined by low-energy electron diffraction and by atom-beam scattering), there is a substantial increase in the screening of the photohole. A transition of the electronic structure akin to a metal-nonmetal (metal-insulator) transition is apparent in these final-state effects. The band structure for Hg is similar to the band structure expected for a free-standing film with a free-electron sd band. The delocalization …
Novel Methods For Deposition Of Boron Carbide Films, J. Mazurowski, S. Baral-Tosh, G. Ramseyer, J.T. Spencer, Yoon-Gi Kim, Peter A. Dowben
Novel Methods For Deposition Of Boron Carbide Films, J. Mazurowski, S. Baral-Tosh, G. Ramseyer, J.T. Spencer, Yoon-Gi Kim, Peter A. Dowben
Peter Dowben Publications
By combining pentaborane (B5H9) and decarborane (B10H14) with methane in a plasma reactor, a variety of boron-carbides can be made over a wide range of compositions. The resulting thin films have uniform composition and appear to be polycrystalline.
The Deposition Of Nickel Boride Thin Films By Borane And Metallaborane Cluster Compounds, John A. Glass Jr., Shreyas Kher, Yoon-Gi Kim, Peter A. Dowben, James T. Spencer
The Deposition Of Nickel Boride Thin Films By Borane And Metallaborane Cluster Compounds, John A. Glass Jr., Shreyas Kher, Yoon-Gi Kim, Peter A. Dowben, James T. Spencer
Peter Dowben Publications
The deposition of high purity and controlled stoichiometry metal boride thin-film materials has recently received considerable interest. Borane clusters and their corresponding metal complexes are currently Wig investigated in our laboratories for their utility as unique source materials for the formation of metallic boride thin films by MOCVD. Variable composition nickel boride thin films ranging from 0.1 micron to several microns have been prepared. These new materials have been characterized by SEM, AES and XES. The magnetic properties of these new films have been investigated with torque magnetometry and magneto-optic Kerr effect magnetometry.
Thermal Desorption Of Hg Monolayers From Cu(100), Y.J. Kime, Jiandi Zhang, Peter A. Dowben
Thermal Desorption Of Hg Monolayers From Cu(100), Y.J. Kime, Jiandi Zhang, Peter A. Dowben
Peter Dowben Publications
A two dimensional phase transition from one adlayer structure to another is an inherent part of the thermal desorption of one monolayer of Hg on Cu(100). The energetics of this phase transition have been studied using thermal desorption spectroscopy (TDS). The TDS spectra reflect the coexistence of the two structural phases for a range of Hg exposures. The TDS spectra have been analyzed within a Polanyi-Wigner framework modified to account for the phase transition.
Synchrotron-Radiation-Induced Deposition Of Boron And Boron Carbide Films From Boranes And Carboranes: Decaborane, F. Keith Perkins, R.A. Rosenberg, Sunwoo Lee, Peter A. Dowben
Synchrotron-Radiation-Induced Deposition Of Boron And Boron Carbide Films From Boranes And Carboranes: Decaborane, F. Keith Perkins, R.A. Rosenberg, Sunwoo Lee, Peter A. Dowben
Peter Dowben Publications
Boron has been deposited successfully on Si(111) from the synchrotron-radiation-induced decomposition of decaborane (14), i.e., B10H14. The rate of deposition is limited by the adsorption rate of decaborane (14) on the surface. In addition there is some indication that there is an activation barrier to dissociative adsorption. The synchrotron-radiation- induced growth rate of boron thin films from decaborane (14) is linear with coverage for a large range of thickness, suggesting a constant sticking coefficient for decaborane adsorption at room temperature.
Selective Area Deposition Of Boron On Si(111) Induced By Synchrotron Radiation, R.A. Rosenberg, F.K. Perkins, D.C. Mancini, G.R. Harp, B.P. Tonner, S. Lee, Peter A. Dowben
Selective Area Deposition Of Boron On Si(111) Induced By Synchrotron Radiation, R.A. Rosenberg, F.K. Perkins, D.C. Mancini, G.R. Harp, B.P. Tonner, S. Lee, Peter A. Dowben
Peter Dowben Publications
We have performed the first deposition of boron on Si(111) induced by broadband synchrotron radiation (SR). Contamination-free thin films were grown at room temperature using decaborane (B10H14) as the source gas. After deposition the films were examined using photoelectron microscopy, which showed that film growth was limited to the region illuminated by SR. The temperature of the substrate rose less than 10 K. These results indicate that gas-phase excitations are not important and that the films are deposited by a nonthermal, photoinduced mechanism. Masked exposures demonstrate the potential of this technique for patterned deposition.
Substrate-Induced Magnetic Ordering Of Rare-Earth Overlayers, Peter A. Dowben, D. Lagraffe, Dongqi Li, A. Miller, Ling Zhang, L. Dottl, M. Onellion
Substrate-Induced Magnetic Ordering Of Rare-Earth Overlayers, Peter A. Dowben, D. Lagraffe, Dongqi Li, A. Miller, Ling Zhang, L. Dottl, M. Onellion
Peter Dowben Publications
We have studied the magnetic ordering of terbium overlayers on Cu(100) and Ni(111), using angle-resolved photoemission. The 5p3/2 to 5p1/2 shallow-core-level branching ratios in different photoemission geometries provide a measure of the magnetic ordering in rare-earth-metal overlayers as a result of final-state effects in photoemission. We find that ferromagnetic substrates order paramagnetic terbium overlayers. This induced magnetic ordering is not a crystal-field effect and can be modeled by Ginzburg-Landau theory. Application of Ginzburg-Landau theory to our results suggests that the correlation length of paramagnetic terbium κ-1 is between 2.5 and 3.5 Å. Reversible increases in …