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Title: Effect of surface reactions of low-energy carbon ions on the secondary electron emission of TiN:O thin films

Abstract

Low-energy secondary electron emission coatings are required for antimultipactor applications in several important technologies and their study and development is also a matter of scientific interest. For this purpose, titanium nitride was deposited on Si(100) substrates by reactive sputtering and the influence of low-energy carbon ion bombardment on the secondary electron emission yield of TiN:O coatings was studied. The composition and chemical bonds formed in the films after carbon ion implantation were analyzed by x-ray photoelectron spectroscopy (XPS). XPS revealed the formation of both carbidic and graphitic bonds. N was displaced while Ti-C bonds were formed up to a limiting value of 0.103 for the carbidic carbon atomic fraction, beyond which a graphitic surface layer was deposited. The secondary electron emission yields for TiN:O were measured before and after low-energy CH{sub n}{sup +} ion bombardment and air exposure, and after heating. Initially, the carbon ion implantation reduced the secondary electron emission yield. Then an increase in secondary electron emission was obtained when the excess graphitic carbon was deposited on the sample. On the other hand, subsequent thermal treatment at 700 deg. C of the carburized samples produced a further reduction of the secondary electron emission yield. The maximum yields aremore » about 53% lower for thermal annealed films than for similarly treated previously measured as-deposited layers. A narrowing of XPS peak line shapes is observed as a consequence of the annealing away of structural and chemical defects in the near-surface region. In addition, secondary electron emission (SEE) yield curves were used in a simulation of multipactor discharge. Both experimental multipactor threshold tests and computer multipactor simulations indicate that SEE yield values for low primary-electron energies are the most influencing parameters on multipactor threshold.« less

Authors:
; ; ; ;  [1];  [2];  [3]
  1. Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid 28049 (Spain)
  2. (Spain)
  3. (Netherlands)
Publication Date:
OSTI Identifier:
20979406
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 11; Other Information: DOI: 10.1063/1.2736861; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CARBON IONS; CHEMICAL BONDS; ELECTRON EMISSION; GRAPHITE; ION BEAMS; LAYERS; LIMITING VALUES; SIMULATION; SPUTTERING; SUBSTRATES; SURFACE COATING; THIN FILMS; TITANIUM NITRIDES; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Montero, I., Mohamed, S. H., Garcia, M., Galan, L., Raboso, D., Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049-Madrid, and European Space Research and Technology Center, ESA, 2200 AG Noordwijk. Effect of surface reactions of low-energy carbon ions on the secondary electron emission of TiN:O thin films. United States: N. p., 2007. Web. doi:10.1063/1.2736861.
Montero, I., Mohamed, S. H., Garcia, M., Galan, L., Raboso, D., Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049-Madrid, & European Space Research and Technology Center, ESA, 2200 AG Noordwijk. Effect of surface reactions of low-energy carbon ions on the secondary electron emission of TiN:O thin films. United States. doi:10.1063/1.2736861.
Montero, I., Mohamed, S. H., Garcia, M., Galan, L., Raboso, D., Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049-Madrid, and European Space Research and Technology Center, ESA, 2200 AG Noordwijk. Fri . "Effect of surface reactions of low-energy carbon ions on the secondary electron emission of TiN:O thin films". United States. doi:10.1063/1.2736861.
@article{osti_20979406,
title = {Effect of surface reactions of low-energy carbon ions on the secondary electron emission of TiN:O thin films},
author = {Montero, I. and Mohamed, S. H. and Garcia, M. and Galan, L. and Raboso, D. and Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049-Madrid and European Space Research and Technology Center, ESA, 2200 AG Noordwijk},
abstractNote = {Low-energy secondary electron emission coatings are required for antimultipactor applications in several important technologies and their study and development is also a matter of scientific interest. For this purpose, titanium nitride was deposited on Si(100) substrates by reactive sputtering and the influence of low-energy carbon ion bombardment on the secondary electron emission yield of TiN:O coatings was studied. The composition and chemical bonds formed in the films after carbon ion implantation were analyzed by x-ray photoelectron spectroscopy (XPS). XPS revealed the formation of both carbidic and graphitic bonds. N was displaced while Ti-C bonds were formed up to a limiting value of 0.103 for the carbidic carbon atomic fraction, beyond which a graphitic surface layer was deposited. The secondary electron emission yields for TiN:O were measured before and after low-energy CH{sub n}{sup +} ion bombardment and air exposure, and after heating. Initially, the carbon ion implantation reduced the secondary electron emission yield. Then an increase in secondary electron emission was obtained when the excess graphitic carbon was deposited on the sample. On the other hand, subsequent thermal treatment at 700 deg. C of the carburized samples produced a further reduction of the secondary electron emission yield. The maximum yields are about 53% lower for thermal annealed films than for similarly treated previously measured as-deposited layers. A narrowing of XPS peak line shapes is observed as a consequence of the annealing away of structural and chemical defects in the near-surface region. In addition, secondary electron emission (SEE) yield curves were used in a simulation of multipactor discharge. Both experimental multipactor threshold tests and computer multipactor simulations indicate that SEE yield values for low primary-electron energies are the most influencing parameters on multipactor threshold.},
doi = {10.1063/1.2736861},
journal = {Journal of Applied Physics},
number = 11,
volume = 101,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2007},
month = {Fri Jun 01 00:00:00 EDT 2007}
}
  • The chemical reactions between hyperthermal species from a methane plasma and the boron nitride surface has been studied. In this work we report a x-ray photoemission study of the boron nitride with varying degrees of carburization. The carbon ions react, forming C{endash}B and C{endash}N bonds; for surface carbon concentration, smaller than {approximately}0.30, C{endash}B bonds are formed, while for higher surface carbon concentrations C{endash}B bonds are also observed. In addition, the binding energy difference between the N1s and B1s core levels increases with increasing carbon content of the film. These chemical shifts are interpreted in terms of the decrease of themore » ionicity of the material as a consequence of the increase in the number of C{endash}B and C{endash}N bonds. For surface carbon concentration higher than 0.30 amorphous carbon is also formed that grows and finally forms a surface layer. The valence band spectra of the BNC compounds show that the density of states filling the gap at about 15 eV between the two characteristics peaks of the valence band of BN, marking the nitrogen 2s orbitals and the boron and nitrogen 2p electrons and the orbital hybridization between the 2s of boron and 2p states, increases with increasing carbon fluence as a consequence of the hybridization with carbon orbitals. {copyright} {ital 1997 Materials Research Society.}« less
  • Secondary electron yields from clean, polycrystalline, molybdenum bombarded by He/sup +/ and Ar/sup +/ have been measured for the kinetic energy range 100 ev to 2.5 kev. This covers the transition energy region where electron ejection processes depending on the translational energy of the bombarding particle are superposed on those depending on their potential energies. A definite kinetic energy threshold for electron ejection is observed for He/sup +/ at about 500 ev and for Ar/sup +/ at about 700 ev. For He/sup +/, the yield drops as the energy increases to about 500 ev and, thereafter, increases linearly with energy.more » In the case of Ar/sup +/ gamma is relatively insensitive to beam energy up to the kinetic threshold and, thereafter, increases linearly. The agreement between the observed variation of gamma with ion kinetic energy and a theoretical calculation of the same is discussed. (auth)« less
  • We have measured energy spectra of secondary electrons produced by fast-carbon-cluster C{sub n}{sup +} (n=1-4) bombardment of thin carbon foils (3.2, 7.3, 11.9, and 20.3 {mu}g/cm{sup 2}). For clusters of identical velocity, the convoy-electron yield is enhanced with increasing cluster size n, while the yield of secondary electrons is reduced. The yield of convoy electrons normalized to the number of injected atoms increases proportionally with cluster size n. This proportionality suggests that there is only a weak vicinage effect on the number of primary electrons scattered by the projectile. The vicinage effect observed in low-energy secondary electrons must therefore arisemore » from either transport or transmission through the surface.« less
  • We report the energy and angular distribution of electron double differential cross sections (DDCS) in collision of 6-MeV/u C{sup 6+} ions with molecular hydrogen. We explain the observed distributions in terms of the two-center effect and the Young-type interference effect. The secondary electrons having energies between 1 and 1000 eV are detected at about 10 different emission angles between 30 degree sign and 150 degree sign . The measured data are compared with the state-of-the-art continuum distorted wave-eikonal initial state and the first Born model calculations which use molecular wave function. The single differential cross sections are derived and comparedmore » with the theoretical predictions. The oscillations due to the interference effect are derived in the DDCS ratios using theoretical cross sections for the atomic H target. The effect of the atomic parameters on the observed oscillations is discussed. An evidence of interference effect has also been shown in the single differential cross section. The electron energy dependence of the forward-backward asymmetry parameter shows a monotonically increasing behavior for an atomic target, such as He, which could be explained in terms of the two-center effect only. In contrast, for the molecular H{sub 2} the asymmetry parameter reveals an oscillatory behavior due to the Young-type interference effect superimposed with the two-center effect. The asymmetry parameter technique provides a self-normalized method to reveal the interference oscillation which does not require either a theoretical model or complementary measurements on the atomic H target.« less
  • An experimental investigation was made of how ion velocity and angle of incidence affect the magnitude and uniformity of secondary electron yield from thin amorphous oxide films. Flat target surfaces of Al$sub 2$O$sub 3$ and BeO in a high vacuum of 10$sup -8$--10$sup -9$ torr were bombarded with singly-charged positive ions of Li, Na, K, Rb, Cs, and Ni isotopes. Each of these elements has a different yield versus velocity response. The data are consistent with Parilis and Kishinevskii's prediction of a common velocity threshold. The estimate of the threshold velocity is 5.5 x 10$sup 6$ cm/sec. For a givenmore » element within experimental error, isotopes of different masses but with the same impact velocity produce identical average secondary electron yields. Furthermore, the statistical variances of their secondary electron frequency distributions also are identical. These results demonstrate the absence of an isotope effect on secondary electron emission. In general, secondary electron yield is not linear with ion velocity. Additional results were obtained for MgO and Ta$sub 2$O$sub 5$ surfaces. It was found that secondary electron yield depends strongly on the electronic shell structure of a projectile ion, that is, on its atomic number Z. The data can be interpreted qualitatively using the Fano--Lichten--Barat electron promotion model for ion-atom collisions when the Z's are unequal. A statistical model of secondary electron emission is described in which each ion-atom collision below a surface may result in the release of one or more electrons. In this model the random sequence or order in which target atoms are struck, the unequal amount of electronic excitation generated during collisions of a projectile ion with different kinds of target atoms, and the electronic properties of an oxide surface are all factors which shape the frequency distribution of observed secondary electrons. (auth)« less