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Full-Text Articles in 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 …