Search results for "purity"
showing 10 items of 356 documents
Local structure in Ga1−xInxSe alloys
2021
Abstract In this work we study the local structure of layered G a 1 − x I n x S e alloys by means of X-ray Absorption. We complement our research with a Raman study. The available alloys have compositions close to the host binaries. The dependence of XANES (X-ray Near Edge Structure) features with synchrotron polarization clearly establishes the substitutional character of the alloying cations. Interstitial atoms, if present, remain under the detection limit of the technique. EXAFS (Extended X-ray Absorption Fine Structure) demonstrates the existence of G a − I n bonds in the alloys. The cation-anion bond-lengths in the alloys remain similar to that of the pure compounds. There is no signif…
SnO2 : Sb - A new material for high-temperature MEMS heater applications: Performance and limitations
2007
MEMS micro heater devices capable of long-term operation at temperatures up to 1000 degrees C are presented. The enhanced long-term stability has been achieved by employing antimony-doped tin oxide (SnO2:Sb) as a substitute for the conventionally used noble metal heater resistors. A detailed investigation of its high-temperature stability reveals that degradation is caused by out-diffusion of Sb impurities from the SnO2 film. (c) 2007 Elsevier B.V. All rights reserved.
Thermal behavior of absorbing and scattering glass media containing molecular water impurity
2005
The effect of the presence of molecular water impurity of various concentrations in absorbing and scattering glass media on the temperature field in a layer subjected to thermal infrared radiation is investigated. The analysed medium is treated as a multicomponent medium consisting of glass matrix and water impurity. The effect of radiation on the medium is expressed by heat sources in each component due to absorption of radiation. It is shown that the presence of water impurity in the glass medium should be accounted for in order to predict the temperature distribution during radiation action. The effect of scattering of radiation by water molecules on thermal and diffusive processes in th…
The effects of the intense laser field on donor impurities in a cylindrical quantum dot under the electric field
2011
Abstract For different nitrogen and indium concentrations, intense laser field (ILF) effect on donor impurity binding energy in a cylindrical Ga x In 1 − x N y As 1 − y / GaAs quantum dot (QD) has been studied. Results show that ILF creates an additional confinement on the electronic and impurity states in QD and increases nitrogen and indium concentration effects on electronic states.
Investigation of lanthanum substitution effects in yttrium aluminium garnet: importance of solid state NMR and EPR methods
2020
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The co-reactant role during plasma enhanced atomic layer deposition of palladium
2020
Atomic layer deposition (ALD) of noble metals is an attractive technology potentially applied in nanoelectronics and catalysis. Unlike the combustion-like mechanism shown by other noble metal ALD processes, the main palladium (Pd) ALD process using palladium(ii)hexafluoroacetylacetonate [Pd(hfac)2] as precursor is based on true reducing surface chemistry. In this work, a thorough investigation of plasma-enhanced Pd ALD is carried out by employing this precursor with different plasmas (H2*, NH3*, O2*) and plasma sequences (H2* + O2*, O2* + H2*) as co-reactants at varying temperatures, providing insights in the co-reactant and temperature dependence of the Pd growth per cycle (GPC). At all te…
Electronically induced trapping of hydrogen by impurities in niobium
1984
The binding energies of hydrogen and its isotopes to substitutional impurities Ti, Cr, and V in niobium have been calculated. The hydrogen-metal interaction is based on the effective-medium theory. The wave mechanics of the hydrogenic interstitials are explicity dealt with, and the lattice distortion created by the hydrogen is incorporated through the method of lattice statics. The difference in the electronic structure between impurity and host atoms is shown to be largely responsible for the binding of hydrogen to the impurities. The results are in agreement with recent inelastic neutron scattering experiments. Peer reviewed
Theory of hydrogen and helium impurities in metals
1984
A powerful computational scheme is presented for calculating the static properties of light interstitials in metallic hosts. The method entails (i) the construction of the potential-energy field using the quasiatom concept, (ii) the wave-mechanical solution of the impurity distribution ("zero-point motion"), (iii) calculation of the forces exerted on the adjacent host atoms and their displacements, and (iv) iteration to self-consistency. We investigate self-trapping phenomena in bcc and fcc metals in detail, and calculate both the ground and low-lying excited states. Implications of the wave-mechanical or band picture to diffusion mechanisms and inelastic scattering experiments are discusse…
Plasma-Enhanced Atomic Layer Deposition of Silver Thin Films
2011
Thermal properties of various silver precursors known in the literature were evaluated in order to discover which precursor is the most suitable one for plasma-enhanced atomic layer deposition (PEALD) of silver thin films. Ag(fod)(PEt3) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) was found to be the best choice. Using Ag(fod)(PEt3) together with plasma-activated hydrogen, silver thin films were deposited at growth temperatures of 120–150 °C, and ALD-type saturative growth was achieved at 120–140 °C. At 120 °C, the growth rate was 0.03 nm per cycle. The plasma exposure time had also an effect on the growth rate: with shorter exposure times, the growth rate was lower over…
Electronic Structure Changes across the Metamagnetic Transition in FeRh via Hard X-Ray Photoemission
2012
International audience; Stoichiometric FeRh undergoes a temperature-induced antiferromagnetic (AFM) to ferromagnetic (FM) transition at similar to 350 K. In this Letter, changes in the electronic structure accompanying this transition are investigated in epitaxial FeRh thin films via bulk-sensitive valence-band and core-level hard x-ray photoelectron spectroscopy with a photon energy of 5.95 keV. Clear differences between the AFM and FM states are observed across the entire valence-band spectrum and these are well reproduced using density-functional theory. Changes in the 2p core levels of Fe are also observed and interpreted using Anderson impurity model calculations. These results indicat…