Abstract

The influence of the TiO2 concentration (≦10 at. %) on the structural and the optical properties of CaF2-rich CaF2–TiO2 composite films fabricated by reactive ion-assisted codeposition are investigated. The composition-dependent properties are found to be similar to those reported for composite films with higher TiO2 concentrations. The surface roughness of CaF2 films and their adhesion to a glass substrate are greatly improved by the addition of a small amount of TiO2. These composite films are quite suitable for IR coatings as a transparent, low-refractive-index material at wavelengths of <10 µm. Two examples, a Fabry–Perot filter and a mid-IR dichroic filter, of applications that use CaF2–TiO2 with 10-at. % TiO2 and Ge as low- and high-refractive-index coating materials, respectively, are presented.

© 1999 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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1998

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

1997

1994

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

1993

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

F. A. Modine, D. Lubben, J. B. Bates, “Electrical conduction in CaF2 and CaF2–A12O3 nanocomposite films on A12O3 substrates,” J. Appl. Phys. 74, 2658–2664 (1993).
[CrossRef]

1991

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

1989

N. S. Gluck, H. Sankur, W. J. Gunning, “Ion-assisted laser deposition of CaF2 thin films at low temperatures,” J. Vac. Sci. Technol. A 7, 2983–2987 (1989).
[CrossRef]

S. Scaglione, D. Flori, G. Emiliani, “Modification of mechanical properties of e-gun evaporated MgF2 and CaF2 thin films under ion beam bombardment,” Appl. Surf. Sci. 43, 224–227 (1989).
[CrossRef]

1975

1968

K. Nagata, “Inhomogeneity in refractive index of evaporated MgF2 films,” Jpn. J. Appl. Phys. 7, 1181–1185 (1968).
[CrossRef]

1957

1949

J. Bannon, C. K. Coogan, “Thin evaporated calcium fluoride films,” Nature 163, 62–63 (1949).
[CrossRef]

Abeles, F.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Al-Robaee, M. S.

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

Bannon, J.

J. Bannon, C. K. Coogan, “Thin evaporated calcium fluoride films,” Nature 163, 62–63 (1949).
[CrossRef]

Bates, J. B.

F. A. Modine, D. Lubben, J. B. Bates, “Electrical conduction in CaF2 and CaF2–A12O3 nanocomposite films on A12O3 substrates,” J. Appl. Phys. 74, 2658–2664 (1993).
[CrossRef]

Coogan, C. K.

J. Bannon, C. K. Coogan, “Thin evaporated calcium fluoride films,” Nature 163, 62–63 (1949).
[CrossRef]

Emiliani, G.

S. Scaglione, D. Flori, G. Emiliani, “Modification of mechanical properties of e-gun evaporated MgF2 and CaF2 thin films under ion beam bombardment,” Appl. Surf. Sci. 43, 224–227 (1989).
[CrossRef]

Fisson, S.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Flori, D.

S. Scaglione, D. Flori, G. Emiliani, “Modification of mechanical properties of e-gun evaporated MgF2 and CaF2 thin films under ion beam bombardment,” Appl. Surf. Sci. 43, 224–227 (1989).
[CrossRef]

Frigerio, J. M.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Gluck, N. S.

N. S. Gluck, H. Sankur, W. J. Gunning, “Ion-assisted laser deposition of CaF2 thin films at low temperatures,” J. Vac. Sci. Technol. A 7, 2983–2987 (1989).
[CrossRef]

Gunning, W. J.

N. S. Gluck, H. Sankur, W. J. Gunning, “Ion-assisted laser deposition of CaF2 thin films at low temperatures,” J. Vac. Sci. Technol. A 7, 2983–2987 (1989).
[CrossRef]

Heavens, O. S.

Ho, F. C.

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

Hoffman, R. A.

Hopkins, R. H.

Hua, M.-Y.

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

Juliet, P.

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

Kramer, W. E.

Krishna, M. G.

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

Lubben, D.

F. A. Modine, D. Lubben, J. B. Bates, “Electrical conduction in CaF2 and CaF2–A12O3 nanocomposite films on A12O3 substrates,” J. Appl. Phys. 74, 2658–2664 (1993).
[CrossRef]

Marechal, N.

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

Modine, F. A.

F. A. Modine, D. Lubben, J. B. Bates, “Electrical conduction in CaF2 and CaF2–A12O3 nanocomposite films on A12O3 substrates,” J. Appl. Phys. 74, 2658–2664 (1993).
[CrossRef]

Mohau, S.

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

Nagata, K.

K. Nagata, “Inhomogeneity in refractive index of evaporated MgF2 films,” Jpn. J. Appl. Phys. 7, 1181–1185 (1968).
[CrossRef]

Nguyen Van, V.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Palik, E. D.

E. D. Palik, Handbook of Optical Constants of Solids II (Academic, New York, 1991), pp. 815–836.

E. D. Palik, Handbook of Optical Constants of Solids (Academic, Orlando, Fla., 1985), pp. 475, 566.

Pauleau, Y.

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

Pawlewicz, W. T.

Quesnel, E.

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

Rao, K. N.

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

Rivory, J.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Sankur, H.

N. S. Gluck, H. Sankur, W. J. Gunning, “Ion-assisted laser deposition of CaF2 thin films at low temperatures,” J. Vac. Sci. Technol. A 7, 2983–2987 (1989).
[CrossRef]

Scaglione, S.

S. Scaglione, D. Flori, G. Emiliani, “Modification of mechanical properties of e-gun evaporated MgF2 and CaF2 thin films under ion beam bombardment,” Appl. Surf. Sci. 43, 224–227 (1989).
[CrossRef]

Shiau, S.-C.

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

Smith, S. D.

Traylor Kruschwitz, J. D.

Tsai, R.-Y.

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

Vuye, G.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Wang, Y.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

Wei, C.-T.

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

Appl. Opt.

Appl. Surf. Sci.

S. Scaglione, D. Flori, G. Emiliani, “Modification of mechanical properties of e-gun evaporated MgF2 and CaF2 thin films under ion beam bombardment,” Appl. Surf. Sci. 43, 224–227 (1989).
[CrossRef]

J. Appl. Phys.

F. A. Modine, D. Lubben, J. B. Bates, “Electrical conduction in CaF2 and CaF2–A12O3 nanocomposite films on A12O3 substrates,” J. Appl. Phys. 74, 2658–2664 (1993).
[CrossRef]

N. Marechal, E. Quesnel, P. Juliet, Y. Pauleau, “Radio frequency sputter deposition and properties of calcium fluoride thin films,” J. Appl. Phys. 74, 5203–5211 (1993).
[CrossRef]

J. Opt. Soc. Am.

J. Vac. Sci. Technol. A

M. S. Al-Robaee, M. G. Krishna, K. N. Rao, S. Mohau, “Optical properties of ion-assisted deposited CeO2 films,” J. Vac. Sci. Technol. A 9(6) , 3048–3053 (1991).
[CrossRef]

N. S. Gluck, H. Sankur, W. J. Gunning, “Ion-assisted laser deposition of CaF2 thin films at low temperatures,” J. Vac. Sci. Technol. A 7, 2983–2987 (1989).
[CrossRef]

Jpn. J. Appl. Phys.

K. Nagata, “Inhomogeneity in refractive index of evaporated MgF2 films,” Jpn. J. Appl. Phys. 7, 1181–1185 (1968).
[CrossRef]

Nature

J. Bannon, C. K. Coogan, “Thin evaporated calcium fluoride films,” Nature 163, 62–63 (1949).
[CrossRef]

Opt. Eng.

R.-Y. Tsai, S.-C. Shiau, F. C. Ho, M.-Y. Hua, “Composition-dependent structural, optical, mechanical, and moisture resistant properties of CaF2–TiO2 composite films prepared by reactive ion-assisted codeposition,” Opt. Eng. 37, 2625–2629 (1998).
[CrossRef]

R.-Y. Tsai, M.-Y. Hua, C.-T. Wei, F. C. Ho, “Characterizations of composite TiO2–MgF2 films prepared by reactive ion-assisted coevaporation,” Opt. Eng. 33, 3411–3418 (1994).
[CrossRef]

Other

E. D. Palik, Handbook of Optical Constants of Solids II (Academic, New York, 1991), pp. 815–836.

J. Rivory, S. Fisson, J. M. Frigerio, V. Nguyen Van, G. Vuye, Y. Wang, F. Abeles, “Growth of low and high refractive index dielectric films: an in situ ellipsometry study,” in Optical Interference Coatings, F. Abeles, ed., Proc. SPIE2253, 1328–1335 (1994).

E. D. Palik, Handbook of Optical Constants of Solids (Academic, Orlando, Fla., 1985), pp. 475, 566.

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Figures (7)

Fig. 1
Fig. 1

XRD patterns of CaF2-rich CaF2–TiO2 films deposited by IACD on glass substrates plotted as a function of the TiO2 composition.

Fig. 2
Fig. 2

Measured normal-incidence UV–VIS transmittance spectra of CaF2-rich CaF2–TiO2 composite films of various TiO2 concentrations and deposited on glass substrates.

Fig. 3
Fig. 3

Refractive indices for CaF2–TiO2 composite films of various TiO2 concentrations plotted versus the wavelength range of 0.3–12 µm.

Fig. 4
Fig. 4

Measured normal-incidence IR-transmittance spectra of CaF2-rich CaF2–TiO2 composite films of various TiO2 concentrations and deposited on Si substrates.

Fig. 5
Fig. 5

Calculated and measured normal-incidence transmittance spectra for a single FP filter with the following structure: Si substrate/HLH 2L HLH/air (H and L correspond to quarter-wave layers of Ge and the CaF2–TiO2 composite, respectively; see text for details). The calculated spectra are shown with (open circles) and without (dashed curve) the cone-angle effect of FTIR taken into account.

Fig. 6
Fig. 6

Calculated and measured normal-incidence transmittance spectra of a mid-IR dichroic filter that consists of 11 alternating layers of Ge and CaF2–TiO2 on a Si substrate. All composite films have a TiO2 concentration of 10 at. %.

Fig. 7
Fig. 7

Measured normal-incidence transmittance spectra of a mid-IR dichroic filter of Fig. 6 before and after it is subjected to 95% relative humidity at 65 °C for 3 h.

Tables (3)

Tables Icon

Table 1 Measured rms Surface Roughness Rq and Adhesion of CaF2-Rich CaF2–TiO2 Composite Films Deposited on Si Wafers and Glass Substrates as a Function of the TiO2 Concentration

Tables Icon

Table 2 Cauchy Parameters A and B of CaF2-Rich CaF2–TiO2 Composite Films as a Function of the TiO2 Concentrationa

Tables Icon

Table 3 Designed Construction Parameters of a Mid-IR Dichroic Filter (11 Alternating Layers of Ge and CaF2–TiO2) Deposited on a Si Substrate at the Reference Wavelengtha

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