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- Boron carbide (4)
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Articles 211 - 240 of 284
Full-Text Articles in Physics
Auger Electron Spectroscopy Of Free Argon Clusters, A. Knop, D.N. Mcilroy, Peter A. Dowben, E. Ruhl
Auger Electron Spectroscopy Of Free Argon Clusters, A. Knop, D.N. Mcilroy, Peter A. Dowben, E. Ruhl
Peter Dowben Publications
Auger electron spectra and Auger yields of free argon clusters in the Ar(2p) excitation regime are reported. The Auger yield spectra show characteristic changes as a function of cluster size. The results indicate that the Auger yield signal originates primarily from the surface of the clusters. The results are compared to bulk-sensitive experimental techniques, such as total electron yields (TEY), zero kinetic energy electron (ZEKE) spectra for variable size clusters, as well as Auger yield spectra of condensed argon multilayers.
Fabrication Of Large Arrays Of Micron-Scale Magnetic Features By Selective Area Organometallic Chemical Vapor Deposition, D. Welipitiya, Y.L. He, Jiandi Zhang, P.I. Oden, T. Thundat, R.J. Warmack, Ismail Gobulukoglu, Z.S. Shan, David J. Sellmyer, Peter A. Dowben
Fabrication Of Large Arrays Of Micron-Scale Magnetic Features By Selective Area Organometallic Chemical Vapor Deposition, D. Welipitiya, Y.L. He, Jiandi Zhang, P.I. Oden, T. Thundat, R.J. Warmack, Ismail Gobulukoglu, Z.S. Shan, David J. Sellmyer, Peter A. Dowben
Peter Dowben Publications
We demonstrate that it is possible to deposit a wide range of magnetic features, using photoassisted selective area organometallic chemical vapor deposition. Large arrays of identical micron-scale Ni features were deposited on a Si(111) wafer by this method. Their magnetic properties were studied by alternating gradient force magnetometry as well as magnetic force microscopy. Our morphological and magnetic measurements show that the structures are spatially well defined, and the magnetic properties are related to the structural shapes of the features. This method can be adapted to the fabrication of smaller-scale magnetic and electronic devices. ©1996 American Institute of Physics.
Spin Polarization Of The Conduction Bands And Secondary Electrons Of Gd(0001), Dongqi Li, J. Pearson, S.D. Bader, D.N. Mcilroy, C. Waldfried, Peter A. Dowben
Spin Polarization Of The Conduction Bands And Secondary Electrons Of Gd(0001), Dongqi Li, J. Pearson, S.D. Bader, D.N. Mcilroy, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
Angle- and spin-resolved photoemission was utilized to investigate the 5d bulk bands and the surface state of Gd(0001) in the temperature range of 130–350 K. The bulk bands at 1–2 eV below the Fermi energy EF show Stoner-like behavior, while the temperature dependence of the surface state near EF indicates spin-mixing behavior due to fluctuating local 5d moments. The secondary electron spectra of the Gd surfaces both before and after initial oxygen adsorption show a polarization dip at low kinetic energies due to the extra scattering channel for minority electrons via the unoccupied 4f level. The temperature dependencies …
Oxygen Induced Suppression Of The Surface Magnetization Of Gd(0001), D.N. Mcilroy, C. Waldfried, Dongqi Li, J. Pearson, S.D. Bader, D.-J. Huang, P.D. Johnson, R.F. Sabiryanov, Sitaram Jaswal, Peter A. Dowben
Oxygen Induced Suppression Of The Surface Magnetization Of Gd(0001), D.N. Mcilroy, C. Waldfried, Dongqi Li, J. Pearson, S.D. Bader, D.-J. Huang, P.D. Johnson, R.F. Sabiryanov, Sitaram Jaswal, Peter A. Dowben
Peter Dowben Publications
The effects of oxygen adsorption on the surface magnetization of Gd(0001) have been determined by measuring the polarization of the Gd 4f core levels and the oxygen induced states with spin-resolved photoemission. Calculations of the partial density of states of O/Gd(0001) using the LMTO-ASA method support the photoemission measurements, which indicate that oxidation occurs at low coverages. The loss of surface magnetic order with oxygen exposure is explained in terms of decreasing indirect coupling.
Ultraviolet And Electron Radiation Induced Fragmentation Of Adsorbed Ferrocene, Dulip Welipitiya, A. Green, J.P. Woods, Peter A. Dowben, Brian W. Robertson, Dongjin Byun, Jiandi Zhang
Ultraviolet And Electron Radiation Induced Fragmentation Of Adsorbed Ferrocene, Dulip Welipitiya, A. Green, J.P. Woods, Peter A. Dowben, Brian W. Robertson, Dongjin Byun, Jiandi Zhang
Peter Dowben Publications
From thermal desorption spectroscopy we find that ferrocene, Fe(C5H5)2, adsorbs and desorbs associatively on Ag(100). Photoemission results indicate that the initially adsorbed surface species closely resembles that of molecular ferrocene. The shift in photoemission binding energies relative to the gas phase is largely independent of the molecular orbital. We find that ultraviolet light does lead to partial fragmentation of the ferrocene and that the molecular fragments are much more strongly bound to the surface than the associatively adsorbed ferrocene. Since fragmentation occurs only in the presence of incident radiation, selective area deposition from this …
Fabrication Of Boron-Carbide Boron Heterojunction Devices, Seong-Don Hwang, Dongjin Byun, N.J. Ianno, Peter A. Dowben, H.R. Kim
Fabrication Of Boron-Carbide Boron Heterojunction Devices, Seong-Don Hwang, Dongjin Byun, N.J. Ianno, Peter A. Dowben, H.R. Kim
Peter Dowben Publications
We have succeeded in the fabrication of a boron–carbide/boron diode on an aluminum substrate, and a boron–carbide/boron junction field effect transistor. Our results suggest that with respect to the approximately 2 eV band gap pure boron material, 0.9 eV band gap boron–carbide (B5C) acts as a p-type material. Both boron and boron–carbide (B5C) thin films were fabricated from single source borane cage molecules using plasma enhanced chemical vapor deposition (PECVD). Epitaxial growth does not appear to be a requirement. ©1996 American Institute of Physics.
Forming B1-XCX Semiconductor Devices By Chemical Vapor Deposition, Peter A. Dowben
Forming B1-XCX Semiconductor Devices By Chemical Vapor Deposition, Peter A. Dowben
Peter Dowben Publications
Active semiconductor devices including heterojunction diodes and thin film transistors are formed by PECVD deposition of a boron carbide thin film on an N-type substrate. The boron to carbon ratio of the deposited material is controlled so that the film has a suitable band gap energy. Boron carbides such as B4.7C, B7.2C and B19C have suitable band gap energies between 0.8 and 1.7 eV. The stoichiometry of the film can be selected by varying the partial pressure of precursor gases, such as nido pentaborane and methane. The precursor gas or gases are energized, e.g., …
Spin Polarization Of The Conduction Bands Of Gd(0001)*, Dongqi Li, J. Pearson, S.D. Bader, D. N. Mcilroy, C. Waldfried, Peter A. Dowben
Spin Polarization Of The Conduction Bands Of Gd(0001)*, Dongqi Li, J. Pearson, S.D. Bader, D. N. Mcilroy, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
Angle- and spin-resolved photoemission was utilized to investigate the 5d bulk bands and the surface state of Gd(0001) in the temperature range of 130 - 350 K. The bulk bands at 1-2 eV below the Fermi energy EF show Stoner-like behavior, while the temperature dependence of the surface state near EF indicates spin-mixing behavior due to fluctuating local 5d moments. The secondary electron spectra of the Gd surfaces both before and after initial oxygen adsorption show a polarization dip at low kinetic energies due to the extra scattering channel for minority electrons via the unoccupied 4ƒ level. The …
Correlation Between Screening And Electron Effective Mass Across The Nonmetal-Metal Transition In Ultrathin Films, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Correlation Between Screening And Electron Effective Mass Across The Nonmetal-Metal Transition In Ultrathin Films, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Peter Dowben Publications
Angle-resolved photoemission and resonant photoemission have been used to determine the relative changes of the electron effective mass and the screening parameter across the nonmetal to metal transition in the magnesium thin films on Mo(112). Both the screening length and the electron effective mass exhibit a gradual change with Mg coverage in the transition range between half and one monolayer. The relationship of these two different measures of metallicity is in surprisingly good agreement with the relationship predicted by theory for the Mott-Hubbard transition. Our results indicate the importance of electron-electron correlation within the overlayer.
A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl
A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl
Peter Dowben Publications
In this paper we will review the performance of a “miniature” single pass cylindrical mirror analyzer (CMA) which we have used successfully in a variety of experiments. The underlying premise behind this CMA design was to minimize spatial requirements while maintaining an acceptable level of instrumental resolution. While we are presenting the results of a single pass cylindrical mirror analyzer, improvements on the present design, such as going to a double pass design, will undoubtedly improve the instrumental resolution.
A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl
A Novel Design For A Small Retractable Cylindrical Mirror Analyzer, D.N. Mcilroy, Peter A. Dowben, A. Knop, E. Ruhl
Peter Dowben Publications
In this paper we will review the performance of a “miniature” single pass cylindrical mirror analyzer (CMA) which we have used successfully in a variety of experiments. The underlying premise behind this CMA design was to minimize spatial requirements while maintaining an acceptable level of instrumental resolution. While we are presenting the results of a single pass cylindrical mirror analyzer, improvements on the present design, such as going to a double pass design, will undoubtedly improve the instrumental resolution.
Mercury Surface-Plasmon Dispersion: Experiment And Theory, Bong-Ok Kim, Geunseop Lee, E. Ward Plummer, Peter A. Dowben, A. Liebsch
Mercury Surface-Plasmon Dispersion: Experiment And Theory, Bong-Ok Kim, Geunseop Lee, E. Ward Plummer, Peter A. Dowben, A. Liebsch
Peter Dowben Publications
Momentum-resolved inelastic electron spectroscopy has been utilized to measure the surface-plasmon dispersion and damping for thick Hg films grown onto a Cu(100) substrate. Hg has been investigated since it offers an opportunity to examine the effects of the crystal potential on the surface-plasmon dispersion, and to correlate the measurements on a surface with those for collective excitations in clusters. The effects of the electronic band structure of Hg can be seen in the energy and width of the surface plasmon as a function of momentum transfer q∥. Dynamical response calculations were performed for a semi-infinite electron gas where several important …
Spin-Polarized Photoemission Studies Of The Exchange Splitting Of The Gd 5d Electrons Near The Curie Temperature, Dongqi Li, J. Pearson, S.D. Bader, D.N. Mcilroy, C. Waldfried, Peter A. Dowben
Spin-Polarized Photoemission Studies Of The Exchange Splitting Of The Gd 5d Electrons Near The Curie Temperature, Dongqi Li, J. Pearson, S.D. Bader, D.N. Mcilroy, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
Spin-polarized photoemission was employed to investigate the temperature dependence of the exchange splitting of Gd(0001) for both the surface state near the Fermi level EF and the 5d bulk bands. The bulk bands at 1–2 eV below E F show Stoner-like behavior where two peaks with opposite spin polarization shift toward each other as the temperature increases. In contrast, the temperature dependence of the surface state indicates spin-mixing behavior due to fluctuating local moments. These differences are attributed to the degree of itinerancy of the 5d electrons in the two cases.
Resonant Photoemission Studies Of The Thickness Dependence Of The Unoccupied Gd 5D Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Resonant Photoemission Studies Of The Thickness Dependence Of The Unoccupied Gd 5D Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Peter Dowben Publications
Ultrathin Gd films have been studied with constant initial-state spectroscopy (CIS) of photoemission utilizing linearly polarized light of synchrotron radiation. The photoemission cross section of the 5d surface state near EF shows strong photon energy dependence, i.e., sharp peaks in CIS spectra near the Gd 5p1/2 absorption edge. These peaks originate from resonant photoemission processes involving the occupied 5p and unoccupied 5d levels of the surface atoms. The symmetry of the unoccupied states were determined experimentally by changing the polarization of light, where pp-polarized light excites only to the unoccupied dz2 …
Scanning Tunneling Microscopy Study Of Intermediates In The Dissociative Adsorption Of Closo-1,2-Dicarbadodecaborane On Si(111), J.M. Carpinelli, E. Ward Plummer, Dongjin Byun, Peter A. Dowben
Scanning Tunneling Microscopy Study Of Intermediates In The Dissociative Adsorption Of Closo-1,2-Dicarbadodecaborane On Si(111), J.M. Carpinelli, E. Ward Plummer, Dongjin Byun, Peter A. Dowben
Peter Dowben Publications
Closo-1,2-dicarbadodecaborane (C2B10H12) is a source compound found to be suitable for the deposition of a high resistivity form of boron-carbide (B5C), and the fabrication of boron-rich semiconductor devices. A scanning tunneling microscope (STM) was used to image these molecular icosahedra on Si(111)-(7x7). Molecular decomposition (tip induced and otherwise! produced a boron-carbide/silicon interface with pronounced heterojunction electronic characteristics. In STM, this interface is characterized by a disordering of the Si(111)-(7x7) reconstruction. We suggest, based on Auger electron spectroscopy data and low-energy electron diffraction observations, that boron atoms from the dissociated source molecules …
Resonant Photoemission Studies Of The Thickness Dependence Of The Unoccupied Gd 5D Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Resonant Photoemission Studies Of The Thickness Dependence Of The Unoccupied Gd 5D Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Peter Dowben Publications
Ultrathin Gd films have been studied with constant initial-state spectroscopy (CIS) of photoemission utilizing linearly polarized light of synchrotron radiation. The photoemission cross section of the 5d surface state near EF shows strong photon energy dependence, i.e., sharp peaks in CIS spectra near the Gd 5p1/2 absorption edge. These peaks originate from resonant photoemission processes involving the occupied 5p and unoccupied 5d levels of the surface atoms. The symmetry of the unoccupied states were determined experimentally by changing the polarization of light, where p-polarized light excites only to the unoccupied dz2 …
Scanning Tunneling Microscopy Study Of Intermediates In The Dissociative Adsorption Of Closo-1,2-Dicarbadodecaborane On Si(111), J.M. Carpinelli, E.W. Plummer, Dongjin Byun, Peter A. Dowben
Scanning Tunneling Microscopy Study Of Intermediates In The Dissociative Adsorption Of Closo-1,2-Dicarbadodecaborane On Si(111), J.M. Carpinelli, E.W. Plummer, Dongjin Byun, Peter A. Dowben
Peter Dowben Publications
Closo-1,2-dicarbadodecaborane (C2B10H12) is a source compound found to be suitable for the deposition of a high resistivity form of boron-carbide (B5C), and the fabrication of boron-rich semiconductor devices. A scanning tunneling microscope (STM) was used to image these molecular icosahedra on Si(111)-(7 x 7). Molecular decomposition (tip induced and otherwise) produced a boron-carbide/silicon interface with pronounced heterojunction electronic characteristics. In STM, this interface is characterized by a disordering of the Si(111)-(7 x 7) reconstruction. We suggest, based on Auger electron spectroscopy data and low-energy electron diffraction observations, that boron atoms from the …
The Paramagnetic Correlation Length Of Mn Thin Films, D.N. Mcilroy, Peter A. Dowben
The Paramagnetic Correlation Length Of Mn Thin Films, D.N. Mcilroy, Peter A. Dowben
Peter Dowben Publications
We have utilized Ginzberg-Landau mean field theory to analyze the branching ratio and soft X-ray magnetic circular dichroism measurements of the L3 and L2 adsorption edges of thin Mn overlayers on ferromagnetic fcc Co(001) at room temperature. We have determined a short range magnetic correlation of 4.25Å and that the long range magnetic order has a decay length of 1.29Å. These results indicate that the first monolayer of Mn ferromagnetically couple with the Co substrate. The paramagnetic Mn layer exhibits short range magnetic order, but lacks long range magnetic order. Due to the exponential decrease of both the …
Electron-Beam-Induced Patterned Deposition Of Allylcyclopentadienyl Palladium Using Scanning Tunneling Microscopy, D.S. Saulys, A. Ermakov, E.L. Garfunkel, Peter A. Dowben
Electron-Beam-Induced Patterned Deposition Of Allylcyclopentadienyl Palladium Using Scanning Tunneling Microscopy, D.S. Saulys, A. Ermakov, E.L. Garfunkel, Peter A. Dowben
Peter Dowben Publications
Scanning tunneling microscopy has been used to study the electron-induced decomposition of allylcyclopentadienyl palladium [Pd(η3-C3H5)( η5-C5H5)] and subsequent deposition on a Si(111) surface. Deposition occurs via an electron impact mechanism on either the tip or surface, depending on the bias polarity, and is observed with voltages of 2.75 V. This is close to the predicted condensed phase dissociation energy of 2.3 eV for Pd(η3-C3H5)(η5-C5H5)→Pd+C3H5+C5H5. Metallic deposits of nanometer …
Resonant Photoemission Studies Of Thickness Dependence Of The Unoccupied Gd 5d Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Resonant Photoemission Studies Of Thickness Dependence Of The Unoccupied Gd 5d Bands, Peter A. Dowben, Dongqi Li, Jiandi Zhang, M. Onellion
Peter Dowben Publications
Ultrathin Gd films have been studied with constant initial-state spectroscopy (CIS) of photoemission utilizing linearly polarized light of synchrotron radiation. The photoemission cross-section of the 5d surface state near EF shows strong photon energy dependence, i.e., sharp peaks in CIS spectra near the Gd 5p1/2 adsorption edge. These peaks originate from resonant photoemission processes involving the occupied 5p and unoccupied 5d levels of the surface atoms. The symmetry of the unoccupied states were determined experimentally by changing the polarization of light, where p-polarized light excites only to the unoccupied dz2 or dxz,yz states and s-polarized light …
Novel Methods For The Fabrication Of Ferromagnetic Nickel And Nickel Boride Thin Films, D. Zych, A. Patwa, S.S. Kher, N.M. Boag, Peter A. Dowben
Novel Methods For The Fabrication Of Ferromagnetic Nickel And Nickel Boride Thin Films, D. Zych, A. Patwa, S.S. Kher, N.M. Boag, Peter A. Dowben
Peter Dowben Publications
Metal-rich nickel boride thin films fabricated from boron-containing precursor compounds by a cluster deposition process are shown to be ferromagnetic. The metal-rich films fabricated by this approach exhibit hysteresis curves similar to those obtained for pure nickel foils. These films are a mixture of pure nickel and the Ni3B nickel boride phases. It is postulated that the hysteresis curves with smaller remnant magnetizations obtained from these films are a consequence of Ni3B inclusions within the films. Other novel organometallic source compounds for nickel chemical-vapor deposition are briefly reviewed. Journal of Applied Physics is copyrighted by The …
Layer-By-Layer Growth Of Hg On W(110), Jiandi Zhang, Dongqi Li, Peter A. Dowben
Layer-By-Layer Growth Of Hg On W(110), Jiandi Zhang, Dongqi Li, Peter A. Dowben
Peter Dowben Publications
Using photoelectron spectroscopy, the overlayer electronic structure was observed to he modulated by the Hg growth mode for Hg adsorbed on W(110) at 200 K. The Hg layer-by-layer growth was also characterized by variations in the ratio between the Hg 5d shallow core level and W 4f photoemission intensities. This layer-by-layer growth occurs in spite of surprisingly weak electronic interactions between the adatoms and the substrate.
Layer-By-Layer Growth Of Hg On W(110), Jiandi Zhang, Dongqi Li, Peter A. Dowben
Layer-By-Layer Growth Of Hg On W(110), Jiandi Zhang, Dongqi Li, Peter A. Dowben
Peter Dowben Publications
Using photoelectron spectroscopy, the overlayer electronic structure was observed to he modulated by the Hg growth mode for Hg adsorbed on W(110) at 200 K. The Hg layer-by-layer growth was also characterized by variations in the ratio between the Hg 5d shallow core level and W 4f photoemission intensities. This layer-by-layer growth occurs in spite of surprisingly weak electronic interactions between the adatoms and the substrate.
Changes In Electron Localization And Density Of States Near EF Across The Nonmetal-Metal Transition In Mg Overlayers, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Changes In Electron Localization And Density Of States Near EF Across The Nonmetal-Metal Transition In Mg Overlayers, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Peter Dowben Publications
A nonmetal-to-metal transition in Mg monolayers on Mo(112) has been indicated by photoemission and resonant photoemission. The dramatic changes of the density of states, the dispersion of bands near EF, and screening are observed across the nonmetal-to-metal transition. The changes of the resonance photon energy and the intensity of Mg 2p→εd excitation, with different coverages, indicate that there exists a correlation between the electronic structure (particularly final-state screening effects) and the overlayer structure. The commensurate-to-incommensurate transition beyond 0.5 monolayer of coverage corresponds to the overlayer nonmetal-to-metal transition, which is due to the hybridization of Mg s and p …
Heterojunction Fabrication By Selective Area Chemical Vapor Deposition Induced By Synchrotron Radiation, Dongjin Byun, Seong-Don Hwang, Peter A. Dowben, F. Keith Perkins, F. Filips, N.J. Ianno
Heterojunction Fabrication By Selective Area Chemical Vapor Deposition Induced By Synchrotron Radiation, Dongjin Byun, Seong-Don Hwang, Peter A. Dowben, F. Keith Perkins, F. Filips, N.J. Ianno
Peter Dowben Publications
We have fabricated a B5C, boron-carbide/Si(111) heterojunction diode by the synchrotron radiation-induced decomposition of orthocarborane. This diode can be compared with similar boron-carbide/Si(111) heterojunction diodes fabricated by plasma enhanced chemical vapor deposition. The synchrotron radiation induced chemical vapor deposition is postulated to occur via the decomposition of weakly chemisorbed species and the results suggest that “real-time'' projection lithography (selective area deposition) of boron-carbide devices is possible.
Unoccupied Surface Electronic Structure Of Gd(0001), Dongqi Li, Peter A. Dowben, J.E. Ortega, F.J. Himpsel
Unoccupied Surface Electronic Structure Of Gd(0001), Dongqi Li, Peter A. Dowben, J.E. Ortega, F.J. Himpsel
Peter Dowben Publications
The unoccupied surface electronic structure of Gd(0001) was investigated with high-resolution inverse-photoemission spectroscopy. An empty surface state near EF is observed at Γ¯. Two other surface-sensitive features are also revealed at 1.2 and 3.1 eV above the Fermi level. Hydrogen adsorption on Gd surfaces was used to distinguish the surface-sensitive features from the bulk features. The unoccupied bulk-band critical points are determined to be Γ3- at 1.9 eV and A1 at 0.8 eV.
The Structural Homogeneity Of Boron Carbide Thin Films Fabricated Using Plasma-Enhanced Chemical Vapor Deposition From B5H9+Ch4, Sunwoo Lee, J. Mazurowski, W.L. O'Brien, Q.Y. Dong, J.J. Jia, T.A. Callcott, K.E. Miyano, D.L. Ederer, D.R. Mueller, Peter A. Dowben
The Structural Homogeneity Of Boron Carbide Thin Films Fabricated Using Plasma-Enhanced Chemical Vapor Deposition From B5H9+Ch4, Sunwoo Lee, J. Mazurowski, W.L. O'Brien, Q.Y. Dong, J.J. Jia, T.A. Callcott, K.E. Miyano, D.L. Ederer, D.R. Mueller, Peter A. Dowben
Peter Dowben Publications
Boron carbide thin films of several B/C ratios have been deposited on Si(111) using plasma-enhanced chemical vapor deposition from nido-pentaborane(9) (B5H9) and methane (CH4). X-ray diffraction studies of boron carbide thin films on Si(111) exhibited characteristic microcrystalline diffraction lines. Soft x-ray emission spectroscopy was used to verify that the local electronic structure and composition of each sample corresponded to a homogeneous solid solution boron carbide phase.
Altering The Gd(0001) Surface Electronic Structure With Hydrogen Adsorption, Dongqi Li, Jiandi Zhang, Peter A. Dowben, M. Onellion
Altering The Gd(0001) Surface Electronic Structure With Hydrogen Adsorption, Dongqi Li, Jiandi Zhang, Peter A. Dowben, M. Onellion
Peter Dowben Publications
Hydrogen adsorption on Gd(0001) has been studied with angle-resolved photoemission. Hydrogen adsorption attenuates the surface state near EF on the clean Gd(0001) surfaces and induces two two-dimensional bands which are at 3.8 eV and about 6 eV near Γ¯. The state with the smaller binding energy has dz2 character at Γ¯ and disperses away from EF about 1 eV. The state at the greater binding energy disperses toward EF about 0.5–1 eV. At low substrate temperatures (120–130 K), the hydrogen chemisorption on the Gd(0001) surface results in a work-function decrease of 0.2 eV. The correlation between the …
Experimental Determination Of The Unoccupied Bands Of W(110), Dongqi Li, Peter A. Dowben, J.E. Ortega, F.J. Himpsel
Experimental Determination Of The Unoccupied Bands Of W(110), Dongqi Li, Peter A. Dowben, J.E. Ortega, F.J. Himpsel
Peter Dowben Publications
Inverse photoemission from W(110) has been used to determine the dispersion of the unoccupied energy bands along the tungsten ΓΣN line. The critical points are determined to be Γ12 at 2.6 eV, N1 at 2.2 eV, and the lower limit of N4 at 3.2 eV. The upper bound of the lifetime broadening is estimated as 0.3-0.4 eV at 2-3 eV above EF. The image state is observed at 4.5 eV above EF, or 0.7 eV in binding energy, relative to the vacuum level.
Canted Magnetic Moments At The Gd(0001) Surface, Dongqi Li, Jiandi Zhang, Peter A. Dowben, K. Garrison, P.D. Johnson, H. Tang, T.G. Walker, H. Hopster, J.C. Scott, D. Weller, D.P. Pappas
Canted Magnetic Moments At The Gd(0001) Surface, Dongqi Li, Jiandi Zhang, Peter A. Dowben, K. Garrison, P.D. Johnson, H. Tang, T.G. Walker, H. Hopster, J.C. Scott, D. Weller, D.P. Pappas
Peter Dowben Publications
With spin polarized electron spectroscopies, we have investigated ordered GD(0001) films deposited on W(110). The photoemission features of the gadolinium 5d surface state, the 4f levels, and the background exhibit considerable spin polarization along the same direction in the plane of the film, indicative of ferromagnetic coupling between the surface and the bulk. The 4f spin polarized photoemission data provides strong evidence that the surface 4f polarization differs from the bulk 4f polarization for Gd(0001). Our temperature dependent measurements with spin polarized secondary electron spectroscopy conclusively establishes that the surface of clean Gd(0001) possesses a perpendicular polarization component which persists …