Abstract

Optical constants of amorphous GeOx films as a function of wavelength are determined for the first time, to the best of our knowledge, in thin films grown by laser deposition and dc sputtering of Ge in an oxygen environment. We determined the oxygen content of the films by combining nuclear reaction analysis and Rutherford backscattering spectrometry. Spectroscopic ellipsometry is used to determine the film optical constants. Effective medium modeling is used to simulate the optical properties of the films assuming the films contain a mixture of amorphous Ge and GeO2. The results show that substoichiometric GeOx films behave optically as a mixture of amorphous Ge and GeO2. Films with low oxygen content (x < 1.0) seem to have inhomogeneous oxygen concentrations with depth. The effect of the deposition rate and oxygen pressure (and Ar pressure in sputtered films) on film stoichiometry and optical properties is also discussed.

© 1994 Optical Society of America

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  1. P. A. Tic, P. L. Bocko, “Optical fiber materials,” in Optical Materials, S. Musikant, ed., Vol. of Optical Materials: A Series of Advances (Dekker, New York, 1990), pp. 175–218.
  2. Z. Yin, B. K. Garside, “Low-loss GeO2 optical waveguide fabrication using low deposition rate rf sputtering,” Appl. Opt. 21, 4324–4328 (1982).
    [CrossRef] [PubMed]
  3. T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
    [CrossRef]
  4. J. Beynon, M. M. El-Samanoudy, “Memory phenomena in reactively-evaporated AlOx and GeOx thin films,” J. Mater. Sci. Lett. 6, 1447–1449 (1987).
    [CrossRef]
  5. U. J. Gibson, “Ion beam processing of optical thin films,” Mater. Res. Soc. Symp. Proc. 152, 105–114 (1989).
    [CrossRef]
  6. R. K. Singh, J. Narayan, “Pulsed-laser evaporation technique for deposition of thin films: physics and theoretical model,” Phys. Rev. B 41, 8843–8859 (1990).
    [CrossRef]
  7. H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
    [CrossRef]
  8. J. C. G. de Sande, C. N. Afonso, J. L. Escudero, R. Serna, F. Catalina, E. E. Bernabeu, “Optical properties of laser-deposited a-Ge films: a comparison with sputtered and e-beam-deposited films,” Appl. Opt. 31, 6133–6138 (1992).
    [CrossRef] [PubMed]
  9. A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
    [CrossRef]
  10. C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
    [CrossRef]
  11. B. P. Rai, “On the optical absorption edge in thin GeOx films,” Phys. Status Solidi A 100, K189–K193 (1987).
    [CrossRef]
  12. A. L. Shabalov, M. S. Feldman, “Optical properties of thin GeOx films,” Phys. Status Solidi A 83, K11–K14 (1984).
    [CrossRef]
  13. J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
    [CrossRef]
  14. J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
    [CrossRef]
  15. C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
    [CrossRef]
  16. C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
    [CrossRef]
  17. D. E. Aspnes, “Optical properties of thin films,” Thin Solid Films 89, 249–262 (1982).
    [CrossRef]
  18. L. Pajasova, “Optical properties of GeO2 in the ultraviolet region,” Czech. J. Phys. B 19, 1265–1271 (1969).
    [CrossRef]
  19. B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
    [CrossRef]
  20. J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
    [CrossRef]
  21. K. H. Müller, “Ion beam induced epitaxial vapor-phase growth: a molecular-dynamics study,” Phys. Rev. B 35, 7906–7913 (1987).
    [CrossRef]

1992 (2)

1991 (2)

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

1990 (2)

R. K. Singh, J. Narayan, “Pulsed-laser evaporation technique for deposition of thin films: physics and theoretical model,” Phys. Rev. B 41, 8843–8859 (1990).
[CrossRef]

C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
[CrossRef]

1989 (3)

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
[CrossRef]

U. J. Gibson, “Ion beam processing of optical thin films,” Mater. Res. Soc. Symp. Proc. 152, 105–114 (1989).
[CrossRef]

1988 (2)

J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
[CrossRef]

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

1987 (4)

K. H. Müller, “Ion beam induced epitaxial vapor-phase growth: a molecular-dynamics study,” Phys. Rev. B 35, 7906–7913 (1987).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

J. Beynon, M. M. El-Samanoudy, “Memory phenomena in reactively-evaporated AlOx and GeOx thin films,” J. Mater. Sci. Lett. 6, 1447–1449 (1987).
[CrossRef]

B. P. Rai, “On the optical absorption edge in thin GeOx films,” Phys. Status Solidi A 100, K189–K193 (1987).
[CrossRef]

1984 (1)

A. L. Shabalov, M. S. Feldman, “Optical properties of thin GeOx films,” Phys. Status Solidi A 83, K11–K14 (1984).
[CrossRef]

1982 (3)

Z. Yin, B. K. Garside, “Low-loss GeO2 optical waveguide fabrication using low deposition rate rf sputtering,” Appl. Opt. 21, 4324–4328 (1982).
[CrossRef] [PubMed]

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

D. E. Aspnes, “Optical properties of thin films,” Thin Solid Films 89, 249–262 (1982).
[CrossRef]

1969 (1)

L. Pajasova, “Optical properties of GeO2 in the ultraviolet region,” Czech. J. Phys. B 19, 1265–1271 (1969).
[CrossRef]

Afonso, C. N.

J. C. G. de Sande, C. N. Afonso, J. L. Escudero, R. Serna, F. Catalina, E. E. Bernabeu, “Optical properties of laser-deposited a-Ge films: a comparison with sputtered and e-beam-deposited films,” Appl. Opt. 31, 6133–6138 (1992).
[CrossRef] [PubMed]

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
[CrossRef]

Akahira, N.

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

Al-Ani, S. K. J.

J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
[CrossRef]

Aspnes, D. E.

D. E. Aspnes, “Optical properties of thin films,” Thin Solid Films 89, 249–262 (1982).
[CrossRef]

Bauda, G.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Bermejo, D.

C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
[CrossRef]

Bernabeu, E. E.

Besse, J. P.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Beynon, J.

J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
[CrossRef]

J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
[CrossRef]

J. Beynon, M. M. El-Samanoudy, “Memory phenomena in reactively-evaporated AlOx and GeOx thin films,” J. Mater. Sci. Lett. 6, 1447–1449 (1987).
[CrossRef]

Bocko, P. L.

P. A. Tic, P. L. Bocko, “Optical fiber materials,” in Optical Materials, S. Musikant, ed., Vol. of Optical Materials: A Series of Advances (Dekker, New York, 1990), pp. 175–218.

Bondot, P.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Caperaa, C.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Catalina, F.

J. C. G. de Sande, C. N. Afonso, J. L. Escudero, R. Serna, F. Catalina, E. E. Bernabeu, “Optical properties of laser-deposited a-Ge films: a comparison with sputtered and e-beam-deposited films,” Appl. Opt. 31, 6133–6138 (1992).
[CrossRef] [PubMed]

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
[CrossRef]

de Sande, J. C. G.

El-Samanoudy, M. M.

J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
[CrossRef]

J. Beynon, M. M. El-Samanoudy, “Memory phenomena in reactively-evaporated AlOx and GeOx thin films,” J. Mater. Sci. Lett. 6, 1447–1449 (1987).
[CrossRef]

El-Samanoudy, M. M. A. G.

J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
[CrossRef]

Escudero, J. L.

Feldman, M. S.

A. L. Shabalov, M. S. Feldman, “Optical properties of thin GeOx films,” Phys. Status Solidi A 83, K11–K14 (1984).
[CrossRef]

Fessier, P.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Fogarassy, E.

A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
[CrossRef]

Fuchs, C.

A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
[CrossRef]

Garside, B. K.

Gibson, U. J.

U. J. Gibson, “Ion beam processing of optical thin films,” Mater. Res. Soc. Symp. Proc. 152, 105–114 (1989).
[CrossRef]

Izumi, H.

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Jacquet, M.

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Messier, R.

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

Morishita, T.

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Müller, K. H.

K. H. Müller, “Ion beam induced epitaxial vapor-phase growth: a molecular-dynamics study,” Phys. Rev. B 35, 7906–7913 (1987).
[CrossRef]

Narayan, J.

R. K. Singh, J. Narayan, “Pulsed-laser evaporation technique for deposition of thin films: physics and theoretical model,” Phys. Rev. B 41, 8843–8859 (1990).
[CrossRef]

Ohata, K.

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Ohta, T.

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

Ortega, C.

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

Pajasova, L.

L. Pajasova, “Optical properties of GeO2 in the ultraviolet region,” Czech. J. Phys. B 19, 1265–1271 (1969).
[CrossRef]

Pilione, L. J.

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

Rai, B. P.

B. P. Rai, “On the optical absorption edge in thin GeOx films,” Phys. Status Solidi A 100, K189–K193 (1987).
[CrossRef]

Sawada, T.

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Serna, R.

Shabalov, A. L.

A. L. Shabalov, M. S. Feldman, “Optical properties of thin GeOx films,” Phys. Status Solidi A 83, K11–K14 (1984).
[CrossRef]

Short, E. L.

J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
[CrossRef]

Siejka, J.

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

Siffert, P.

A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
[CrossRef]

Singh, R. K.

R. K. Singh, J. Narayan, “Pulsed-laser evaporation technique for deposition of thin films: physics and theoretical model,” Phys. Rev. B 41, 8843–8859 (1990).
[CrossRef]

Slaoui, A.

A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
[CrossRef]

Solis, J.

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

Takenaga, M.

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

Tanaka, S.

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Tic, P. A.

P. A. Tic, P. L. Bocko, “Optical fiber materials,” in Optical Materials, S. Musikant, ed., Vol. of Optical Materials: A Series of Advances (Dekker, New York, 1990), pp. 175–218.

Vedam, K.

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

Vega, F.

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

Yamashita, T.

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

Yang, B.

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

Yehoda, J. E.

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

Yin, Z.

Appl. Opt. (2)

Appl. Phys. Lett. (1)

H. Izumi, K. Ohata, T. Sawada, T. Morishita, S. Tanaka, “Direct observation of ions in laser plume onto the substrate,” Appl. Phys. Lett. 59, 597–599 (1991).
[CrossRef]

Appl. Surf. Sci. (2)

C. N. Afonso, F. Vega, J. Solis, F. Catalina, C. Ortega, J. Siejka, “Laser ablation of Ge in an oxygen environment: plasma and film properties,” Appl. Surf. Sci. 54, 175–179 (1991).
[CrossRef]

C. N. Afonso, R. Serna, F. Catalina, D. Bermejo, “Good-quality Ge films grown by excimer laser deposition,” Appl. Surf. Sci. 46, 249–253 (1990).
[CrossRef]

Czech. J. Phys. B (1)

L. Pajasova, “Optical properties of GeO2 in the ultraviolet region,” Czech. J. Phys. B 19, 1265–1271 (1969).
[CrossRef]

J. Appl. Phys. (2)

A. Slaoui, E. Fogarassy, C. Fuchs, P. Siffert, “Properties of silicon dioxide films prepared by pulsed-laser ablation,” J. Appl. Phys. 71, 590–596 (1992).
[CrossRef]

T. Ohta, M. Takenaga, N. Akahira, T. Yamashita, “Thermal changes of optical properties observed in some suboxide thin films,” J. Appl. Phys. 53, 8497–8500 (1982).
[CrossRef]

J. Mater. Sci. (1)

J. Beynon, M. M. El-Samanoudy, E. L. Short, “Evaluation of the composition of reactively evaporated GeOx thin films from optical transmission and XPS data,” J. Mater. Sci. 23, 4363–4368 (1988).
[CrossRef]

J. Mater. Sci. Lett. (2)

J. Beynon, M. M. El-Samanoudy, “Memory phenomena in reactively-evaporated AlOx and GeOx thin films,” J. Mater. Sci. Lett. 6, 1447–1449 (1987).
[CrossRef]

J. Beynon, M. M. A. G. El-Samanoudy, S. K. J. Al-Ani, “Optical properties of GeOx thin films,” J. Mater. Sci. Lett. 8, 786–788 (1989).
[CrossRef]

J. Vac. Sci. Technol. A (1)

J. E. Yehoda, B. Yang, K. Vedam, R. Messier, “Investigation of the void structure in amorphous germanium thin films as a function of low-energy ion bombardment,” J. Vac. Sci. Technol. A 6, 1631–1635 (1988).
[CrossRef]

Mater. Res. Bull. (1)

C. Caperaa, G. Bauda, J. P. Besse, P. Bondot, P. Fessier, M. Jacquet, “Preparation and characterization of germanium oxide thin films,” Mater. Res. Bull. 24, 1361–1367 (1989).
[CrossRef]

Mater. Res. Soc. Symp. Proc. (1)

U. J. Gibson, “Ion beam processing of optical thin films,” Mater. Res. Soc. Symp. Proc. 152, 105–114 (1989).
[CrossRef]

Phys. Rev. B (3)

R. K. Singh, J. Narayan, “Pulsed-laser evaporation technique for deposition of thin films: physics and theoretical model,” Phys. Rev. B 41, 8843–8859 (1990).
[CrossRef]

B. Yang, L. J. Pilione, J. E. Yehoda, K. Vedam, R. Messier, “Nonuniformity in void concentration between the initial and final growth stage of sputtered a-Ge films studied using spectroscopic ellipsometry,” Phys. Rev. B 36, 6206–6208 (1987).
[CrossRef]

K. H. Müller, “Ion beam induced epitaxial vapor-phase growth: a molecular-dynamics study,” Phys. Rev. B 35, 7906–7913 (1987).
[CrossRef]

Phys. Status Solidi A (2)

B. P. Rai, “On the optical absorption edge in thin GeOx films,” Phys. Status Solidi A 100, K189–K193 (1987).
[CrossRef]

A. L. Shabalov, M. S. Feldman, “Optical properties of thin GeOx films,” Phys. Status Solidi A 83, K11–K14 (1984).
[CrossRef]

Thin Solid Films (1)

D. E. Aspnes, “Optical properties of thin films,” Thin Solid Films 89, 249–262 (1982).
[CrossRef]

Other (1)

P. A. Tic, P. L. Bocko, “Optical fiber materials,” in Optical Materials, S. Musikant, ed., Vol. of Optical Materials: A Series of Advances (Dekker, New York, 1990), pp. 175–218.

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Figures (6)

Fig. 1
Fig. 1

Film configurations that we used to simulate the ellipsometric parameters by varying the a-Ge/a-GeO2 ratio: (a) single- and (b) two-layer models.

Fig. 2
Fig. 2

Experimental evolution of the reflectivity of LD films normalized to the reflectivity of the substrate as a function of the deposited number of Ge atoms for films grown in (1) vacuum and at different oxygen pressures: (2) 4 × 10−4 Torr, (3) 7 × 10−4 Torr, (4) 3.5 × 10−3 Torr, and (5) 5 × 10−3 Torr. Simulated curves for pure a-Ge (□) and GeO2 (⋄) films are also included for comparison.

Fig. 3
Fig. 3

(a) Real and (b) imaginary parts of the refractive index of LD (solid curve) and DC-S (dashed curve) GeO x films deposited at an Ar pressure of 4 × 10−3 Torr with different oxygen content: (1) x = 0.27, (2) x = 0.54, (3) x = 0.82, (4) x = 0.91, (5) x = 1.27, and (6) x = 2.00. We determined the stoichiometry to within 6% by NRA–RBS measurements.

Fig. 4
Fig. 4

Ratio of the number of oxygen to Ge atoms as a function of the oxygen pressure during deposition of LD films (○, ●) and DC-S films deposited at an Ar pressure of 4 × 10−3 Torr (□, ■). We grew LD films by using a constant energy density (8.6 J/cm2), and we grew DC-S films at a deposition rate of 0.25 nm s−1. We determined the O/Ge ratio by NRA–RBS (○, □) and by simulation of the SE parameters using the single-layer model (●, ■). The curves are guidelines for NRA–RBS determined data.

Fig. 5
Fig. 5

(a) Magnification of Fig. 4 in the low oxygen pressure range for LD (○, ●, ⊙) and DC-S (□, ■, ⊡) films. (b) Results obtained for DC-S films grown at 4 × 10−3 (□, ■, ⊡) and 7 × 10−3 Torr (△, ▲, ◬) Ar pressure. We determined the ratio of oxygen to Ge atoms by RBS–NRA (○, □, △) and by simulation of the SE parameters using the single-layer (●, ■, ▲) model and the two-layer (⊙, ⊡, ◬) model. The lines are guidelines for NRA–RBS determined data.

Fig. 6
Fig. 6

Ratio of the number of oxygen to Ge atoms as a function of the deposition rate in at/cm2s for LD (○, ●, ⊙) and DC-S (□, ■, ⊡) films deposited at an Ar pressure of 4 × 10−3 Torr and at an oxygen pressure of 4 × 10−4 Torr. We calculated the O/Ge ratio by NRA–RBS (○, □) and by simulations of the SE parameters using the single-layer model (●, ■) and the two-layer model (⊙, ⊡). The curves are guidelines for NRA–RBS determined data.

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