Abstract

Ion-beam sputter deposition of tantalum oxide films was investigated for possible optical coating applications. Optical properties of such films were found to be a sensitive function of oxygen-to-argon ratio in the ion beam. Refractive index and absorption coefficient were determined in the 250–2000-nm wavelength range by spectrophotometric transmissivity. The different bonding states of the tantalum atoms were revealed by x-ray photoelectron spectroscopy. The visible wavelength refractive index was found to be 2.18 and optical band gap 4.3 eV, so long as the films did not contain inclusions of metallic tantalum. Films with an admixture of oxygen deficient suboxide components had a low-energy tail of increasing magnitude in the absorption spectrum.

© 1985 Optical Society of America

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  1. F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
    [CrossRef]
  2. W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
    [CrossRef]
  3. P. K. Tien, “Light Waves in Thin Films and Integrated Optics,” Appl. Opt. 10, 2395 (1971).
    [CrossRef]
  4. Y. C. Cheng, W. D. Westwood, “Title,” J. Electron. Mater. 3, 37 (1974).
    [CrossRef]
  5. S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).
  6. W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
    [CrossRef]
  7. T. M. Reith, P. J. Ficalora, “The Reactive Sputtering of Tantalum Oxide: Compositional Uniformity, Phases, and Transport Mechanism,” J. Vac. Sci. Technol. A 1, 1362 (1983).
    [CrossRef]
  8. F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
    [CrossRef]
  9. S. Wilcox, W. D. Westwood, “Anodic Oxidation of Tantalum,” Can. J. Phys. 49, 1543 (1971).
    [CrossRef]
  10. E. E. Khawaja, S. G. Tomlin, “The Optical Properties of Thin Films of Ta2O5 and ZrO2,” Thin Solid Films 30, 361 (1975).
    [CrossRef]
  11. W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
    [CrossRef]
  12. J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
    [CrossRef]
  13. H. R. Kaufman, in Advances in Electronics and Electron Physics, Vol. 36, L. Merton, Ed. (Academic, New York, 1974), p.265.
    [CrossRef]
  14. E. Aktulga, “Optical Parameters of a Weakly Absorbing Film on a Non-Absorbing Substrate by Spectrophotometric Transmissivity,” Ph.D. Thesis, Department of Physics, Istanbul U., Istanbul, Turkey.
  15. H. Deminyont, D. B. Kerwin, J. R. Sites, “Optical Properties of Ion-Beam Sputtered TiO2 Films,” Natl. Bur. Stand. U.S. Spec. Publ. to be published.
  16. F. Urbach, “The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids,” Phys. Rev. 92, 1324 (1953).
    [CrossRef]
  17. J. Tauc, Amorphous and Liquid Semiconductors (Plenum, New York, 1974).
    [CrossRef]
  18. L. Young, Anodic Oxide Films (Academic, London, 1961), p 81.

1983

T. M. Reith, P. J. Ficalora, “The Reactive Sputtering of Tantalum Oxide: Compositional Uniformity, Phases, and Transport Mechanism,” J. Vac. Sci. Technol. A 1, 1362 (1983).
[CrossRef]

J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
[CrossRef]

1982

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

1979

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

1975

E. E. Khawaja, S. G. Tomlin, “The Optical Properties of Thin Films of Ta2O5 and ZrO2,” Thin Solid Films 30, 361 (1975).
[CrossRef]

1974

W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
[CrossRef]

Y. C. Cheng, W. D. Westwood, “Title,” J. Electron. Mater. 3, 37 (1974).
[CrossRef]

1971

S. Wilcox, W. D. Westwood, “Anodic Oxidation of Tantalum,” Can. J. Phys. 49, 1543 (1971).
[CrossRef]

P. K. Tien, “Light Waves in Thin Films and Integrated Optics,” Appl. Opt. 10, 2395 (1971).
[CrossRef]

1953

F. Urbach, “The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids,” Phys. Rev. 92, 1324 (1953).
[CrossRef]

Abella, J. M.

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

Aktulga, E.

E. Aktulga, “Optical Parameters of a Weakly Absorbing Film on a Non-Absorbing Substrate by Spectrophotometric Transmissivity,” Ph.D. Thesis, Department of Physics, Istanbul U., Istanbul, Turkey.

Albella, J. M.

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

Boynton, R. J.

W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
[CrossRef]

Cheng, Y. C.

Y. C. Cheng, W. D. Westwood, “Title,” J. Electron. Mater. 3, 37 (1974).
[CrossRef]

Davis, R. L.

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

Deminyont, H.

H. Deminyont, D. B. Kerwin, J. R. Sites, “Optical Properties of Ion-Beam Sputtered TiO2 Films,” Natl. Bur. Stand. U.S. Spec. Publ. to be published.

Denis, J.

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

Ficalora, P. J.

T. M. Reith, P. J. Ficalora, “The Reactive Sputtering of Tantalum Oxide: Compositional Uniformity, Phases, and Transport Mechanism,” J. Vac. Sci. Technol. A 1, 1362 (1983).
[CrossRef]

Gilstrap, P.

J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
[CrossRef]

Heisig, U.

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

Hickernell, F. S.

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

Ingrey, S. J.

W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
[CrossRef]

Kaufman, H. R.

H. R. Kaufman, in Advances in Electronics and Electron Physics, Vol. 36, L. Merton, Ed. (Academic, New York, 1974), p.265.
[CrossRef]

Kerwin, D. B.

H. Deminyont, D. B. Kerwin, J. R. Sites, “Optical Properties of Ion-Beam Sputtered TiO2 Films,” Natl. Bur. Stand. U.S. Spec. Publ. to be published.

Khawaja, E. E.

E. E. Khawaja, S. G. Tomlin, “The Optical Properties of Thin Films of Ta2O5 and ZrO2,” Thin Solid Films 30, 361 (1975).
[CrossRef]

Martinez-Duart, J. M.

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

Paulson, W. M.

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

Reith, T. M.

T. M. Reith, P. J. Ficalora, “The Reactive Sputtering of Tantalum Oxide: Compositional Uniformity, Phases, and Transport Mechanism,” J. Vac. Sci. Technol. A 1, 1362 (1983).
[CrossRef]

Rubio, F.

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

Rujkorakarn, R.

J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
[CrossRef]

Schiller, S.

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

Sites, J. R.

J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
[CrossRef]

H. Deminyont, D. B. Kerwin, J. R. Sites, “Optical Properties of Ion-Beam Sputtered TiO2 Films,” Natl. Bur. Stand. U.S. Spec. Publ. to be published.

Steinfelder, K.

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

Strümpfel, J.

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

Tauc, J.

J. Tauc, Amorphous and Liquid Semiconductors (Plenum, New York, 1974).
[CrossRef]

Tien, P. K.

Tomlin, S. G.

E. E. Khawaja, S. G. Tomlin, “The Optical Properties of Thin Films of Ta2O5 and ZrO2,” Thin Solid Films 30, 361 (1975).
[CrossRef]

Urbach, F.

F. Urbach, “The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids,” Phys. Rev. 92, 1324 (1953).
[CrossRef]

Westwood, W. D.

W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
[CrossRef]

Y. C. Cheng, W. D. Westwood, “Title,” J. Electron. Mater. 3, 37 (1974).
[CrossRef]

S. Wilcox, W. D. Westwood, “Anodic Oxidation of Tantalum,” Can. J. Phys. 49, 1543 (1971).
[CrossRef]

Wilcox, S.

S. Wilcox, W. D. Westwood, “Anodic Oxidation of Tantalum,” Can. J. Phys. 49, 1543 (1971).
[CrossRef]

Young, L.

L. Young, Anodic Oxide Films (Academic, London, 1961), p 81.

Appl. Opt.

Can. J. Phys.

S. Wilcox, W. D. Westwood, “Anodic Oxidation of Tantalum,” Can. J. Phys. 49, 1543 (1971).
[CrossRef]

J. Electron. Mater.

Y. C. Cheng, W. D. Westwood, “Title,” J. Electron. Mater. 3, 37 (1974).
[CrossRef]

J. Vac. Sci. Technol.

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Title,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

W. M. Paulson, F. S. Hickernell, R. L. Davis, “Effects of Deposition Parameters on Optical Loss for rf-Sputtered Ta2O5 and Si3N4 Waveguides,” J. Vac. Sci. Technol. 16, 307 (1979).
[CrossRef]

F. Rubio, J. M. Abella, J. Denis, J. M. Martinez-Duart, “Optical Properties of Reactively Sputtered Ta2O5 Films,” J. Vac. Sci. Technol. 21, 1043 (1982).
[CrossRef]

J. Vac. Sci. Technol. A

T. M. Reith, P. J. Ficalora, “The Reactive Sputtering of Tantalum Oxide: Compositional Uniformity, Phases, and Transport Mechanism,” J. Vac. Sci. Technol. A 1, 1362 (1983).
[CrossRef]

J.Vac. Sci. Technol.

W. D. Westwood, R. J. Boynton, S. J. Ingrey, “Effect of Pressure on the Properties of Reactively Sputtered Ta2O5,” J.Vac. Sci. Technol. 11, 381 (1974).
[CrossRef]

Opt. Eng.

J. R. Sites, P. Gilstrap, R. Rujkorakarn, “Ion-Beam Sputter Deposition of Optical Coatings,” Opt. Eng. 22, 447 (1983).
[CrossRef]

Phys. Rev.

F. Urbach, “The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids,” Phys. Rev. 92, 1324 (1953).
[CrossRef]

Thin Solid Films

E. E. Khawaja, S. G. Tomlin, “The Optical Properties of Thin Films of Ta2O5 and ZrO2,” Thin Solid Films 30, 361 (1975).
[CrossRef]

F. Rubio, J. Denis, J. M. Albella, J. M. Martinez-Duart, “Title,” Thin Solid Films 90, 405 (1982).
[CrossRef]

S. Schiller, U. Heisig, K. Steinfelder, J. Strümpfel, “Title,” Thin Solid Films 63, 363 (1979).

Other

J. Tauc, Amorphous and Liquid Semiconductors (Plenum, New York, 1974).
[CrossRef]

L. Young, Anodic Oxide Films (Academic, London, 1961), p 81.

H. R. Kaufman, in Advances in Electronics and Electron Physics, Vol. 36, L. Merton, Ed. (Academic, New York, 1974), p.265.
[CrossRef]

E. Aktulga, “Optical Parameters of a Weakly Absorbing Film on a Non-Absorbing Substrate by Spectrophotometric Transmissivity,” Ph.D. Thesis, Department of Physics, Istanbul U., Istanbul, Turkey.

H. Deminyont, D. B. Kerwin, J. R. Sites, “Optical Properties of Ion-Beam Sputtered TiO2 Films,” Natl. Bur. Stand. U.S. Spec. Publ. to be published.

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Figures (7)

Fig. 1
Fig. 1

XPS spectra of a metallic tantalum thin film with a native oxide overlayer.

Fig. 2
Fig. 2

Transmittance spectra of four typical samples: T0, bare substrate; (a) stoichiometric oxide; (b) suboxide; (c), (d) cermet films; λcf, cutoff wavelength [λ < λcf, T(λ) = 0]; λth, threshold wavelength [λ > λth, T+(λ) = T0(λ)].

Fig. 3
Fig. 3

Dispersion curves of refractive index and extinction coefficient: (a) stoichiometric oxide; (b) suboxide; (c1), (c2) cermet films.

Fig. 4
Fig. 4

Wavelength dependence of absorption coefficient: (a) stoichiometric oxide; (b), (c) suboxide films with different compositions.

Fig. 5
Fig. 5

(hνα)1/2-vs- plots of tantalum oxide films with various compositions. Ion-beam oxygen fraction during deposition is indicated on each curve.

Fig. 6
Fig. 6

Sputtering time dependence of the XPS O 1s intensity for various composite tantalum oxide films.

Fig. 7
Fig. 7

Real part of complex refractive index vs XPS O 1s peak intensity. The two limits of transparent samples corresponding to suboxide and stoichiometric oxide are indicated on the top scale.

Tables (4)

Tables Icon

Table I Summary of Samples Examined

Tables Icon

Table II Binding Energy of Observed Tantalum States

Tables Icon

Table III Type of Binding and Samples

Tables Icon

Table IV Optical Properties of Ta2O5 Films

Equations (12)

Equations on this page are rendered with MathJax. Learn more.

1 T ( λ ) = u ( λ ) + c ( λ ) · υ ( λ ) ,
u ( λ ) = T ( λ ) + + T ( λ ) 2 T ( λ ) + · T ( λ ) ,
c ( λ ) = T ( λ ) + T ( λ ) 2 T ( λ ) + · T ( λ ) .
n ( λ ) = ½ { [ 8 n s c ( λ ) + ( n s + 1 ) 2 ] 1 / 2 + [ 8 n s c ( λ ) + ( n s 1 ) 2 ] 1 / 2 } ,
d = { 4 [ n ( λ i ) λ i n ( λ i + 1 ) λ i + 1 ] } 1 ,
k ( λ ) = λ 4 π d ln u + u 2 c 2 + σ 2 a + ,
σ = ( n s 2 1 8 n s ) 2 ( n 1 n ) 2 ,
a + = ( n + 1 ) 3 ( n + n s 2 ) 16 n s n 2 ,
n h ( λ ) = n ( λ ) ν k 2 ( λ ) [ ν = f ( n , n s ) ] .
α = A exp [ a ( h ν E 0 ) / k T ] ,
α = B ( h ν E g 0 ) r h ν ,
E g 0 ( eV )

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