Abstract

Thin films of C60 were investigated as protective coatings of Al films to preserve their far-UV (FUV) reflectance by inhibition or retardation of their oxidation. Two methods were used for the overcoating of Al films with approximately one monolayer of C60: (1) deposition of a multilayer film followed by temperature desorption of all but one monolayer and (2) direct deposition of approximately one-monolayer film. We exposed both types of sample to controlled doses of molecular oxygen and water vapor and measured their FUV reflectance before and after exposure to evaluate the achieved protection on the Al films. The whole process of sample preparation, reflectance measurement, sample heating, and oxidation was made without breaking vacuum. Results show that a C60 monolayer protected Al from oxidation to some extent, although FUV reflectance of unprotected Al films was never exceeded. FUV optical constants of C60 films and the FUV reflectance of the C60 film as deposited and as a function of exposure to O2 were also measured.

© 2000 Optical Society of America

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References

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  1. W. R. Hunter, J. F. Osantowski, G. Hass, “Reflectance of Al overcoated with MgF2 and LiF in the wavelength region from 1600 Å to 300 Å at various angles of incidence,” Appl. Opt. 10, 540–544 (1971).
    [CrossRef] [PubMed]
  2. N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
    [CrossRef]
  3. A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
    [CrossRef]
  4. J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Far-ultraviolet reflectance measurements and optical constants of unoxidized Al films,” Appl. Opt. 34, 4892–4899 (1995).
    [CrossRef] [PubMed]
  5. J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Optical constants of Al films in the extreme ultraviolet interval of 82–77 nm,” Appl. Opt. 35, 5692–5697 (1996).
    [CrossRef] [PubMed]
  6. J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Evaporated and ion-beam-deposited MgF2 films as protective coatings for Al films in the FUV.”
  7. H.-J. Hagemann, W. Gudat, C. Kunz, “Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3,” (Deutsches Elektronen-Synchrotron, Hamburg, 1974).
  8. J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Reflectance measurements and optical constants in the EUV for thin films of ion-beam-deposited SiC, Mo, Mg2Si, and InSb, and evaporated Cr.”
  9. J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).
  10. J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Far-UV reflectance of UHV-prepared Al films and its degradation after exposure to O2,” Appl. Opt. 33, 3518–3522 (1994).
    [CrossRef] [PubMed]
  11. J. A. Aznárez, J. I. Larruquert, J. A. Méndez, “Far-ultraviolet absolute reflectometer for optical constant determination of ultrahigh vacuum prepared thin films,” Rev. Sci. Instrum. 67, 497–502 (1996).
    [CrossRef]
  12. Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.
  13. E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
    [CrossRef]

1998

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

1996

J. A. Aznárez, J. I. Larruquert, J. A. Méndez, “Far-ultraviolet absolute reflectometer for optical constant determination of ultrahigh vacuum prepared thin films,” Rev. Sci. Instrum. 67, 497–502 (1996).
[CrossRef]

J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Optical constants of Al films in the extreme ultraviolet interval of 82–77 nm,” Appl. Opt. 35, 5692–5697 (1996).
[CrossRef] [PubMed]

1995

1994

J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Far-UV reflectance of UHV-prepared Al films and its degradation after exposure to O2,” Appl. Opt. 33, 3518–3522 (1994).
[CrossRef] [PubMed]

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

1992

E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
[CrossRef]

1979

Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.

1971

Aznárez, J. A.

Balooch, M.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Dinh, L.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Dykes, J.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Dymshits, Y. I.

Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.

Fink, J.

E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
[CrossRef]

Gall, N. R.

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

Gudat, W.

H.-J. Hagemann, W. Gudat, C. Kunz, “Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3,” (Deutsches Elektronen-Synchrotron, Hamburg, 1974).

Hagemann, H.-J.

H.-J. Hagemann, W. Gudat, C. Kunz, “Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3,” (Deutsches Elektronen-Synchrotron, Hamburg, 1974).

Hamza, A. V.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Hass, G.

Hunter, W. R.

Keski-Kuha, R. A. M.

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Reflectance measurements and optical constants in the EUV for thin films of ion-beam-deposited SiC, Mo, Mg2Si, and InSb, and evaporated Cr.”

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Evaporated and ion-beam-deposited MgF2 films as protective coatings for Al films in the FUV.”

Koch, E. E.

J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).

Korobitsyn, V. A.

Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.

Krafka, C.

J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).

Krätschmer, W.

E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
[CrossRef]

Kunz, C.

H.-J. Hagemann, W. Gudat, C. Kunz, “Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3,” (Deutsches Elektronen-Synchrotron, Hamburg, 1974).

Larruquert, J. I.

J. A. Aznárez, J. I. Larruquert, J. A. Méndez, “Far-ultraviolet absolute reflectometer for optical constant determination of ultrahigh vacuum prepared thin films,” Rev. Sci. Instrum. 67, 497–502 (1996).
[CrossRef]

J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Optical constants of Al films in the extreme ultraviolet interval of 82–77 nm,” Appl. Opt. 35, 5692–5697 (1996).
[CrossRef] [PubMed]

J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Far-ultraviolet reflectance measurements and optical constants of unoxidized Al films,” Appl. Opt. 34, 4892–4899 (1995).
[CrossRef] [PubMed]

J. I. Larruquert, J. A. Méndez, J. A. Aznárez, “Far-UV reflectance of UHV-prepared Al films and its degradation after exposure to O2,” Appl. Opt. 33, 3518–3522 (1994).
[CrossRef] [PubMed]

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Reflectance measurements and optical constants in the EUV for thin films of ion-beam-deposited SiC, Mo, Mg2Si, and InSb, and evaporated Cr.”

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Evaporated and ion-beam-deposited MgF2 films as protective coatings for Al films in the FUV.”

Lynch, D. W.

J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).

Méndez, J. A.

Metel’nikov, A. A.

Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.

Mosley, W. D.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Osantowski, J. F.

Rut’kov, E. V.

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

Sohmen, E.

E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
[CrossRef]

Tontegode, A. Ya.

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

Usufov, M. M.

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

Weaver, J. H.

J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).

Appl. Opt.

Fullerene Sci. Technol.

N. R. Gall, E. V. Rut’kov, A. Ya. Tontegode, M. M. Usufov, “Coadsorption of oxygen and C60 molecules on (100)Mo surface,” Fullerene Sci. Technol. 6, 721–727 (1998).
[CrossRef]

Rev. Sci. Instrum.

J. A. Aznárez, J. I. Larruquert, J. A. Méndez, “Far-ultraviolet absolute reflectometer for optical constant determination of ultrahigh vacuum prepared thin films,” Rev. Sci. Instrum. 67, 497–502 (1996).
[CrossRef]

Sov. J. Opt. Technol.

Y. I. Dymshits, V. A. Korobitsyn, A. A. Metel’nikov, “Effect of heating on the reflectivity of Al coatings in the vacuum ultraviolet,” Sov. J. Opt. Technol. 46, 649–651 (1979), and references therein.

Surf. Sci.

A. V. Hamza, J. Dykes, W. D. Mosley, L. Dinh, M. Balooch, “Reaction and passivation of Al with C60,” Surf. Sci. 318, 368–378 (1994).
[CrossRef]

Z. Phys. B

E. Sohmen, J. Fink, W. Krätschmer, “Electron energy-loss spectroscopy studies on C60 and C70 fullerite,” Z. Phys. B 86, 87–92 (1992).
[CrossRef]

Other

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Evaporated and ion-beam-deposited MgF2 films as protective coatings for Al films in the FUV.”

H.-J. Hagemann, W. Gudat, C. Kunz, “Optical constants from the far infrared to the x-ray region: Mg, Al, Cu, Ag, Au, Bi, C, and Al2O3,” (Deutsches Elektronen-Synchrotron, Hamburg, 1974).

J. I. Larruquert, R. A. M. Keski-Kuha are preparing a manuscript to be called “Reflectance measurements and optical constants in the EUV for thin films of ion-beam-deposited SiC, Mo, Mg2Si, and InSb, and evaporated Cr.”

J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Optical Properties of Metals, publication 18–1 (Fachinformationszentrum, Energie Physik Mathematik, Karlsruhe, Germany, 1981).

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Figures (12)

Fig. 1
Fig. 1

Calculated reflectance of an Al film overcoated with different materials plotted against coating thickness.

Fig. 2
Fig. 2

Schematic view of the experimental equipment: C, capillary; L, lamp; M, monochromator; G, diffraction grating; ENS, entrance slit; EXS, exit slit; MC, modulation chamber; CB, chopper blade; S, aperture stop; RC, reflectometer chamber; C1, C2, C3, channel electron multipliers; MP, MP2, MP3, sample manipulators; SH, sample holder; P1, P2, P3, small conductance pipes; DC, deposition chamber; STC, sample transfer chamber; GV, gate valve.

Fig. 3
Fig. 3

Normal reflectance of a sample with a bare Al film in one area and an Al film coated with a 10-nm-thick C60 film in another area. Reflectance of both areas after sample heating to 500 K for 3 and 18 h is also shown.

Fig. 4
Fig. 4

Normal reflectance of a heated sample with a bare Al film in one area and an Al film coated with a 10-nm-thick C60 film in another area. Reflectance of both areas after sample exposure to doses of molecular oxygen is also shown.

Fig. 5
Fig. 5

Measured reflectance of bare Al and of Al coated with 0.5-, 1.0-, and 1.5-nm C60 films.

Fig. 6
Fig. 6

Reflectance degradation of an unprotected Al film and an Al film coated with a 0.5-nm-thick C60 film plotted versus exposure to molecular oxygen.

Fig. 7
Fig. 7

Reflectance degradation of an unprotected Al film and an Al film coated with a 1.5-nm-thick C60 film versus exposure to molecular oxygen.

Fig. 8
Fig. 8

Reflectance degradation of an unprotected Al film and an Al film coated with a 1.5-nm-thick C60 film plotted versus exposure to water vapor.

Fig. 9
Fig. 9

Reflectance degradation at 104.8 nm of an unprotected Al film and an Al film coated with a 1.5-nm-thick C60 film plotted versus exposure to molecular oxygen and laboratory atmosphere. Solid symbols, state for molecular oxygen doses; open symbols, state for atmosphere doses (given after previous molecular oxygen doses).

Fig. 10
Fig. 10

Reflectance of a 30-nm-thick C60 film plotted versus exposure to molecular oxygen and to laboratory atmosphere (the latter given after the molecular oxygen doses were completed) at four different wavelengths.

Fig. 11
Fig. 11

FUV refractive index of C60 films. Our results are compared with those obtained from electron energy loss spectra by Sohmen et al. 13. Error bars, standard deviation among the different samples.

Fig. 12
Fig. 12

FUV extinction coefficient of C60 films. Our results are compared with those obtained from electron energy loss spectra by Sohmen et al. 13. Error bars, standard deviation among the different samples.

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