Single plane work function coverage relationships for cesium and oxygen coadsorbed on tungsten
Probe field emission studies of work function and energy distribution of cesium-oxygen-tungsten system
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The work function determination and surface characterization of vapor deposited rhenium.
Vapor deposited rhenium surface characteristics and work functions obtained from 1800 to 2300 degrees K by X ray diffraction analysis
Campbell, A. E., Jr.↗
Effect of Electron–Phonon Interaction on the Conductivity and Work Function of Epitaxial Graphene
In the context of the cluster model of epitaxial graphene, the condition for a stepwise change in the charge of carbon atoms under the action of graphene–substrate electron–phonon interaction and an external electric field is derived. Such charge transfer brings about corresponding steps of the static conductivity and work function of epitaxial graphene. Numerical estimates for the case of weak coupling of quasi-free graphene with metal and semiconductor substrates are given.
36 MATERIALS SCIENCE↗
Performance of a cylindrical geometry thermionic converter with an improved work function tungsten emitter.
Cylindrical geometry thermionic converter with vapor deposited W emitter, noting power density performance characteristics, work function and long term stability
Holland, J. W.↗
Surface cleanliness research using the work function technique Final report
Argon ion bombardment and other surface cleaning methods evaluated on polycrystalline tungsten by work function techniques
Brock, F. J.↗
Work function measurements by the field emission retarding potential method
Using the field emission retarding potential method true work functions have been measured for the following monocrystalline substrates: W(110), W(111), W(100), Nb(100), Ni(100), Cu(100), Ir(110) and Ir(111). The electron elastic and inelastic reflection coefficients from several of these surfaces have also been examined near zero primary beam energy.
Swanson, L. W.↗
Work function tuning of plasma-enhanced atomic layer deposited WC{sub x}N{sub y} electrodes for metal/oxide/semiconductor devices
One of the main challenges facing the integration of metals as gate electrodes in advanced MOS devices is control over the Fermi level position at the metal/dielectric interface. In this study, we demonstrate the ability to tune the effective work function (EWF) of W-based electrodes by process modifications of the atomic layer deposited (ALD) films. Tungsten carbo-nitrides (WC{sub x}N{sub y}) films were deposited via plasma-enhanced and/or thermal ALD processes using organometallic precursors. The process modifications enabled us to control the stoichiometry of the WC{sub x}N{sub y} films. Deposition in hydrogen plasma (without nitrogen based reactant) resulted in a stoichiometry of WC{sub 0.4} with primarily W-C chemical bonding, as determined by x-ray photoelectron spectroscopy. These films yielded a relatively low EWF of 4.2 ± 0.1 eV. The introduction of nitrogen based reactant to the plasma or the thermal ALD deposition resulted in a stoichiometry of WC{sub 0.1}N{sub 0.6–0.8} with predominantly W-N chemical bonding. These films produced a high EWF of 4.7 ± 0.1 eV.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Question on the measurement of the metal work function in an electron spectrometer by the secondary-electron emission threshold method
The feasibility of measuring metal work functions using the secondary emission threshold method and an electron spectrometer is demonstrated. Measurements are reported for Nb, Mo, Ta, and W bombarded by Ar(+) ions.
Alov, N. V.↗
Electron theory of metals, bases on Fermi statistics. Part I - General data, flow processes, and work functions
Electron theory of metals based on Fermi statistics and Bose-Einstein statistics - general data, flow processes, and work functions
METAL↗
Nanocluster ionization energies and work function of aluminum, and their temperature dependence
Ionization threshold energies of Al{sub n} (n = 32-95) nanoclusters are determined by laser ionization of free neutral metal clusters thermalized to several temperatures in the range from 65 K to 230 K. The photoion yield curves of cold clusters follow a quadratic energy dependence above threshold, in agreement with the Fowler law of surface photoemission. Accurate data collection and analysis procedures make it possible to resolve very small (few parts in a thousand) temperature-induced shifts in the ionization energies. Extrapolation of the data to the bulk limit enables a determination of the thermal shift of the polycrystalline metal work function, found to be in excellent agreement with theoretical prediction based on the influence of thermal expansion. Small clusters display somewhat larger thermal shifts, reflecting their greater susceptibility to thermal expansion. Ionization studies of free size-resolved nanoclusters facilitate understanding of the interplay of surface, electronic, and lattice properties under contamination-free conditions.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
<theoretical studies on the relationship between the thermionic work function of re- fractory intermetallic compounds and their electronic and crystal structures< progress report letter, 1 jul. - 31 dec. 1964
Thermionic work function of refractory metallic compounds and electronic and crystal structure - emissivity measurement and diode fabrication
DIODE↗
Thermionic scanner pinpoints work function of emitter surfaces
In the electron tube testing, a thermionic scanner makes accurate spatial resolution measurements of the metallic surface work functions of emitters. The scanner determines the emitter function and its local departures from the mean value on a point-by-point basis for display on an oscilloscope.
Rasor, N. S.↗
Improved open-circuit voltage in Cu(In,Ga)Se{sub 2} solar cells with high work function transparent electrodes
Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se{sub 2} (CIGS) solar cells, leading to an open circuit voltage V{sub OC} enhanced by ∼20 mV as compared to reference devices with ZnO:Al (AZO) electrodes. This effect is reproducible in a wide range of contact sheet resistances corresponding to various IOH thicknesses. We present the detailed electrical characterization of glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive oxide (TCO) with different IOH/AZO ratios in the front TCO contact in order to identify possible reasons for the enhanced V{sub OC}. Temperature and illumination intensity-dependent current-voltage measurements indicate that the dominant recombination path does not change when AZO is replaced by IOH, and it is mainly limited to recombination in the space charge region and at the junction interface of the solar cell. The main finding is that the introduction of even a 5 nm-thin IOH layer at the i-ZnO/TCO interface already results in a step-like increase in V{sub OC}. Two possible explanations are proposed and verified by one-dimensional simulations using the SCAPS software. First, a higher work function of IOH as compared to AZO is simulated to yield an V{sub OC} increase by 21 mV. Second, a lower defect density in the i-ZnO layer as a result of the reduced sputter damage during milder sputter-deposition of IOH can also add to a maximum enhanced V{sub OC} of 25 mV. Our results demonstrate that the proper choice of the front TCO contact can reduce the parasitic recombination and boost the efficiency of CIGS cells with improved corrosion stability.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Experimental measurements of the work functions and desorption energies of the systems O-W, O-Mo, O-Re, O-Ta, and Cs-O-Ta.
Thermionic work functions and desorption energies for oxygen on polycrystalline W, Mo and Re filaments, discussing oxygen pressure and filament temperature
Fehrs, D. L.↗
Work function measurements by the field emission retarding potential method.
Description of the theoretical foundation of the field electron retarding potential method, and review of its experimental application to the measurement of single crystal face work functions. The results obtained from several substrates are discussed. An interesting and useful fallout from the experimental approach described is the ability to accurately measure the elastic and inelastic reflection coefficient for impinging electrons to near zero-volt energy.
Strayer, R. W.↗
Accurate vertical ionization energy and work function determinations of liquid water and aqueous solutions
A generalised liquid-phase photoelectron spectroscopy approach is reported, allowing accurate, absolute energy scale ionisation energies of liquid water and aqueous solutions, as well as liquid water's work function to be reported.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Work function measurement of lanthanum-boron compounds
The relationship between emission properties and sample composition is studied for lanthanum-boron compounds. Specifically, the La-B system is considered between 1400 and 2100 K and between LaB(4.24) and LaB(29.2) to determine the phase relationship, chemical activity of the compounds, vapor composition, and vaporization rate. The results indicate that: (1) a blue-colored phase near LaB(9) exists between a purple-colored LaB(6) and elemental boron, (2) vaporization is sufficiently more rapid than diffusion so that great compositional differences exist between the surface and the interior, (3) an activation energy lowers the boron vaporization rate from LaB(6), and (4) a steady-state surface composition between LaB(6.04) and LaB(6.07) exists for freely vaporizing materials as a function of interior composition, purity, and temperature. It is noted that the ultimate life of a thermionic diode is governed by electrode vaporization rate whereas efficiency is governed by the electrode work function.
Jacobson, D. L.↗
Transistor-Based Work-Function Measurement of Metal–Organic Frameworks for Ultra-Low-Power, Rationally Designed Chemical Sensors
A classic challenge in chemical sensing is selectivity. Metal–organic frameworks (MOFs) are an exciting class of materials because they can be tuned for selective chemical adsorption. Adsorption events trigger work-function shifts, which can be detected with a chemical-sensitive field-effect transistor (power ≈microwatts). Here, several case studies were used towards generalizing the sensing mechanism, ultimately towards our metal-centric hypothesis. HKUST-1 was used as a proof-of-principle humidity sensor. The response is thickness independent, meaning the response is surface localized. ZIF-8 is demonstrated to be an NO 2 -sensing material, and the response is dominated by adsorption at metal sites. Finally, MFM-300(In) shows how standard hard–soft acid–base theory can be used to qualitatively predict sensor responses. This paper sets the groundwork for using the tunability of metal–organic frameworks for chemical sensing with distributed, scalable devices.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗