Showing papers on "Work function published in 1973"
TL;DR: In this paper, structural and electronic models are proposed which correlate Goldstein's LEED, Auger, photo-emission, plasmon, and desorption data for negative electron affinity (NEA) on Si(100) surfaces.
286 citations
TL;DR: In this article, a systematic experimental study of Cs and Cs-H 2 adsorption on W (100) surfaces by LEED and work function measurements has been made.
161 citations
TL;DR: Using the field emission retarding potential method, true work functions have been measured for the following monocrystalline substrates: W(110, W(111), W(112), Nb, Ni, Ni(100), Cu, Ir, Ir(110), and Ir(111).
157 citations
TL;DR: In this article, two ordered chemisorbed CO structures were found to form on the clean surface at room temperature using LEED, and the isosteric heat of adosorption, determined from LEED structure stability and from Kelvin-method work function measurements, was approximately 25 kcal/mole for both of the ordered structures.
Abstract: The interaction of CO with a (110) nickel surface has been investigated using a number of techniques. Auger electron spectroscopy was used to follow the chemical composition of the surface. Using LEED, two ordered chemisorbed CO structures were found to form on the clean surface at room temperature. A (2 × 1) structure is stable at pressures above 5 × 10−8torr. This structure is replaced by a one‐dimensionally incoherent structure at lower pressures. The isosteric heat of adosorption, determined from LEED structure stability and from Kelvin‐method work function measurements, was approximately 25 kcal/mole for both of the ordered structures. These structures occur for CO coverages greater than 0.7 monolayer. For coverages below 0.7 the isosteric heat rose to approximately 30 kcal/mole. Work function changes greater than +1.3 eV accompany the reversible CO adsorption. Mass‐spectrometric studies of CO desorption indicated that the adsorbed CO can be removed by heating to 450°K. The mean heat of desorption calculated from CO‐desorption spectra was 25.4± 1.1 kcal/mole. Surface decomposition of CO was caused by heating the sample in CO and also by the interaction of impinging electrons with chemisorbed CO. Interaction with CO caused the reduction of an oxygen‐covered surface for sample temperatures above 500°K. An increase in carbon dioxide was detected in the gas phase during this interaction. Electron energy‐loss spectroscopy provided additional information on the interaction of CO with the surface.
154 citations
TL;DR: In this article, single crystal aluminium surfaces were prepared by auto-epitaxy on these substrates and the work functions of the surfaces were determined photoelectrically, showing a linear relationship between surface atom density and work function for the three faces investigated.
Abstract: (100), (110) and (111) single crystal aluminium substrates were thoroughly outgassed by heating by electron bombardment in ultra high vacuum. Fresh single crystal surfaces were prepared by autoepitaxy on these substrates and the work functions of the surfaces were determined photoelectrically. The general effect of the deposition of an aluminium film on the substrate was to reduce the work function, but annealing the film at temperatures between 473 K and 573 K caused the work function to return to a constant value which was taken to be characteristic of the ordered surface. (100) aluminium surfaces were also prepared by epitaxy on potassium chloride crystals. The effect of argon ion bombardment on a bulk (110) aluminium surface is to increase the work function towards the polycrystalline value, but the characteristic value for the (110) face may be restored by annealing the crystal. There is a linear relationship between surface atom density and work function for the three faces investigated.
140 citations
TL;DR: In this article, the authors used low energy electron diffraction (LEED), Auger electron spectroscopy (AES), mass spectroglobalization and work function measurements.
140 citations
110 citations
TL;DR: In this article, the adsorption of nitrogen on platinum is studied with a field emission microscope equipped with a probe-hole assembly to enable quantitative emission measurements on individual crystal faces, and the results are implemented by photoelectric measurements on platinum films.
87 citations
TL;DR: In this article, single crystals of silver were cleaned by electron-and argon-ion bombardment under conditions of ultra-high vacuum, and the work function of the (111) surface, measured photoelectrically, was (4.74 ± 0.02) eV.
Abstract: Single crystals of silver were cleaned by electron-and argon-ion bombardment under conditions of ultra-high vacuum. The work function of the (111) surface, measured photoelectrically, was (4.74 ± 0.02) eV. Oxygen adsorption caused an increase in the work function of about 0.4 eV.
Unter Ultrahochvakuumbedingungen wurden Silber-Einkristalle mittels Elektronenund Argonionenbeschus gesaubert. Die photo-elektrisch gemessene Austrittsarbeit der (lll)-Oberflache betrug (4,74 ± 0,02) eV. Sauerstoffadsorption verursacht eine Zunahme der Austrittsarbeit von etwa 0,4 eV.
75 citations
TL;DR: In this article, a linear dependence of log i o on Φ, the work function of the metal, first indicated by Bockris and his group for noble metals, is confirmed in this work also for low-Φ metals which usually form anodic oxide films.
69 citations
TL;DR: In this paper, the dependence of the potential emission of electrons from metals on the work function ϕ and Fermi energy eF for metals and the ionization energy of ions was discussed.
Abstract: The paper discusses the dependence of γ-the coefficient of potential emission of electrons from metals on the work function ϕ and Fermi energy eF for metals and the ionization energy of ions Ei . It has been found that in the range 3ϕ 2(∊F + ϕ) Theoretical estimates are in satisfactory agreement with experimental results.
TL;DR: In the absence of chemical reactions with the substrate, the degree of ordering depends on the heats of adsorption, Δ H ads, and the activation energies for surface diffusion, Δ E D ∗ as mentioned in this paper.
TL;DR: In this article, a correlation between changes in the film structure occurring with coverage and features of the work function and adsorption heat concentration dependences was found, and it was concluded that interaction between lithium adatoms on W(112) is highly anisotropic.
TL;DR: In this paper, it was found that the K atoms spread uniformly over the Ni surface and that one well-ordered structure of hexagonal symmetry is formed at 4.9 A K nearest neighbour separation.
TL;DR: In this article, the energy distribution of negative electron affinity (NEA) GaAs: Cs-O has been calculated for various doping concentrations (1 × 1018−2 × 1019 cm−3) and work functions (0.95 −1.15 eV).
Abstract: The energy distribution of electrons emitted from negative electron affinity (NEA) GaAs: Cs–O has been calculated for various doping concentrations (1 × 1018−2 × 1019 cm−3) and work functions (0.95–1.15 eV). It has been assumed that electrons to be emitted have thermalized at the bottom of the conduction band when they reach the surface bent‐band region. The energy distribution of the electrons reaching the surface is determined by their interactions in the bent‐band region and is calculated from a solution of the Boltzmann transport equation. Multiplication of this distribution with an energy‐dependent transmission probability for the surface barrier yields the energy distribution of the emitted electrons. The width of the bent‐band region, and thus the doping concentration of the emitter material, has a significant influence on the shape and width of the distribution and on its location on the energy scale, while the work function mainly affects the magnitude of the distribution. Measured half‐widths of...
TL;DR: In this paper, the authors found that submonolayers of Na on Ge caused drastic increases in SHG, and attributed the increase to the growth of patches of metallic Na.
TL;DR: Work function changes caused by depositing and spreading of copper were measured on the (110, (100), (111) and (211) faces of tungsten crystal by means of field emission microscope as discussed by the authors.
TL;DR: In this article, field emission for the (110) plane of field evaporated and thermally annealed tungsten has been restudied with particular reference to the significance of interpretation of the work function.
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27 Aug 1973TL;DR: In this article, a clean field emission tip is subjected to heating pulses in the presence of an electrostatic field to create thermal field buildup of a selected plane, and the process of heating the tip within the electrostatic fields is repeated until emission is observed from the desired plane.
Abstract: A field emission tip on which a metal adsorbate has been selectively deposited, and a method by which it may be manufactured. In a vacuum, a clean field emission tip is subjected to heating pulses in the presence of an electrostatic field to create thermal field buildup of a selected plane. Emission patterns from the selected plane are observed, and the process of heating the tip within the electrostatic field is repeated until emission is observed from the desired plane. The adsorbate is then evaporated onto the tip. The tip constructed by this process is selectively faceted, with the emitting planar surface having a reduced work function and the non-emitting planar surfaces having an increased work function. A metal adsorbate deposited on the tip so prepared results in a field emitter tip having substantially improved emission characteristics.
TL;DR: In this article, a cylindrical Langmuir probe was inserted into a cathode to investigate the internal plasma, which was used to measure electron temperature Te, electron number density ne and plasma potential Vp in the external plasma.
Abstract: The cathodes studied were similar to those used in the SERTII program and in the initial phase of the present work, except that bifilar heaters were employed. Triple carbonate was usually applied to the internal surfaces, although for long periods of operation, various barium dispensers were used. Experiments were conducted in a diode discharge system and mercury vapor was supplied from a conventional vaporizer. There is considerable evidence to suggest that electron emission occurs internally at constant current density J; about 2 to 5 x 10 amp/m. Although these values of J probably cannot be explained by simple thermionic emission despite the use of barium, considerable field-enhancement may occur in the presence of the dense internal plasma. This extends over an "active zone" having a length determined by the current drawn. Electric fields E in the plasma sheath of about 10 v/m are necessary to account for observed data solely on the basis of this process. Another mechanism capable of giving the required current density and also relying on the presence of an internal plasma covering an active zone is the release of electrons by the impact of metastable atoms. High yields are expected when the excitation energy is close to the work function of the surface, as is the case for mercury impacting on tantalum, and the mechanism does not depend on the presence of an alkali metal. A small cylindrical Langmuir probe near the keeper orifice was used to measure electron temperature Te, electron number density ne and plasma potential Vp in the external plasma. It was also often convenient to use the keeper itself to obtain Te and Vp. Te was in the range 1 to 2.5 x 10K and increased with decrease of flow rate m and increase in /. The former dependence was ascribed to the fall of pressure with m, which resulted in the electrons gaining more energy between collisions. Te was independent of tip temperature T within the range 1000-1400°C. Vp was usually 14-19 v, decreasing as T was raised, and ne was about 10m~. To investigate the internal plasma a cylindrical Langmuir probe was inserted into a cathode. Te, derived from semilogarithmic plots, again decreased with increasing m (Fig. 1). The electron saturation current was used to estimate ne, which
IBM1
TL;DR: In this article, the work function of electron-hole drops in Ge relative to free excitons is measured by an extremely simple and accurate technique, and the threshold excitation power for drop condensation is determined as a function of temperature by observation of the sharp increase in shot noise associated with the drops in a collector junction.
TL;DR: In this paper, the surface potential of the Ge(111) surface as a function of cesium and sodium coverage was measured and it was found that the surface was p-type throughout the entire stable coverage range.
TL;DR: In this article, it was shown that Ni, Au and Pt make blocking contacts while contacts of In, Ga, Al and Bi are ohmic, and that the type of contact made by any of these metals depends on the work function of the metal.
TL;DR: In this article, a facility to determine work function changes was developed in a display-type Varian 120 LEED-Auger apparatus, using the electron beam retarding potential technique.
Abstract: A facility to determine work function changes was developed in a display‐type Varian 120 LEED‐Auger apparatus, using the electron beam retarding potential technique Using the known work function value of a reference material that is atomically clean, as verified by Auger electron spectroscopy, the average work function of other materials of interest can be evaluated
TL;DR: In this article, the work function of stainless steel measured in ultra-high vacuum by the vibrating capacitor method was independent of hydrogen dosage to a pressure of 10 −6 torr.
TL;DR: In this article, the electron-beam stimulated reduction of C concentration on BeO, which requires an oxygen ambient ∼ 10 −7 torr, was studied using Auger spectroscopy.
TL;DR: In this article, it was shown that the diffraction patterns in both cases were identical to those obtained for BaO films on the (0001) Re face described in the preceding paper.
TL;DR: In this article, a method for obtaining a (110) plane of acceptable purity is described, which is characterized by LEED and Auger spectroscopy; effects of annealing and ion-bombardment are given, and the major importance of sulfur diffusing out the crystal in the cleaning process is demonstrated.
TL;DR: It has been found by LEED and work function measurements that the presence of a fractional monolayer of Cs increased the oxidation rate of a Ni(100) surface by about thirteenfold as mentioned in this paper.
TL;DR: In this article, electric field enhancement of photoemission from negative-electron-affinity surfaces on silicon and GaAs has been studied, and it is shown that the electric field increases the escape probability and does not change the spectral response of negativeelectron −affinity surface.
Abstract: Electric field enhancement of photoemission from negative‐electron‐affinity surfaces on silicon and GaAs has been studied. It is shown that the electric field increases the escape probability and does not change the spectral response of negative‐electron‐affinity surfaces. The results are explained by assuming a simple surface potential barrier together with work function lowering by the Schottky effect.