Abstract

We show that the interface between gold and thermally formed cuprous oxide, which emits terahertz radiation when illuminated with ultrafast femtosecond lasers, is in fact an AuCu/Cu2O interface due to the formation of the thermal diffusion alloy AuCu. The alloy enables the formation of a Schottky-barrier-like electric field near the interface which is essential to explain the THz emission from these samples. We confirm the formation of this AuCu layer by x-ray diffraction measurements, ellipsometry, and visual inspection. We determined the frequency-dependent complex refractive indices of the Cu2O and AuCu layer and verified them using reflection spectroscopy measurements. These refractive indices can be used for optimizing the thickness of Cu2O for maximum THz emission from these interfaces.

© 2014 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
    [CrossRef]
  2. Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
    [CrossRef]
  3. G. Ramakrishnan, G. K. P. Ramanandan, A. J. L. Adam, M. Xu, N. Kumar, R. W. A. Hendrikx, and P. C. M. Planken, “Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals,” Opt. Express 21, 16784–16798 (2013).
    [CrossRef]
  4. W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
    [CrossRef]
  5. L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
    [CrossRef]
  6. G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
    [CrossRef]
  7. G. K. P. Ramanandan, G. Ramakrishnan, and P. C. M. Planken, “Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy,” J. Appl. Phys. 111, 123517 (2012).
    [CrossRef]
  8. N. C. J. van der Valk, T. Wenckebach, and P. C. M. Planken, “Full mathematical description of electro-optic detection in optically isotropic crystals,” J. Opt. Soc. Am. B 21, 622–631 (2004).
    [CrossRef]
  9. Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
    [CrossRef]
  10. R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
    [CrossRef]
  11. C. Cretu and E. van der Lingen, “Coloured gold alloys,” Gold Bull. 32, 115–126 (1999).
  12. J. Faber and T. Fawcett, “The powder diffraction file: present and future,” Acta Crystallogr. Sect. B 58, 325–332 (2002).
    [CrossRef]
  13. J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).
  14. H. Fujiwara, Spectroscopic Ellipsometry: Principles and Applications (Wiley, 2007).
  15. J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
    [CrossRef]
  16. O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
    [CrossRef]

2013 (2)

G. Ramakrishnan, G. K. P. Ramanandan, A. J. L. Adam, M. Xu, N. Kumar, R. W. A. Hendrikx, and P. C. M. Planken, “Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals,” Opt. Express 21, 16784–16798 (2013).
[CrossRef]

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

2012 (1)

G. K. P. Ramanandan, G. Ramakrishnan, and P. C. M. Planken, “Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy,” J. Appl. Phys. 111, 123517 (2012).
[CrossRef]

2011 (3)

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
[CrossRef]

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

2009 (1)

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

2005 (1)

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

2004 (1)

2002 (1)

J. Faber and T. Fawcett, “The powder diffraction file: present and future,” Acta Crystallogr. Sect. B 58, 325–332 (2002).
[CrossRef]

1999 (2)

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

C. Cretu and E. van der Lingen, “Coloured gold alloys,” Gold Bull. 32, 115–126 (1999).

1994 (1)

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

1990 (1)

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

1979 (1)

L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
[CrossRef]

Adam, A. J. L.

Alexander, M.

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Auston, D. H.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Bohara, R. C.

L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
[CrossRef]

Braat, J. J. M.

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

Bungay, C. L.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Cao, H.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Chong, Y.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Cretu, C.

C. Cretu and E. van der Lingen, “Coloured gold alloys,” Gold Bull. 32, 115–126 (1999).

Darrow, J. T.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Davazoglou, D.

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

Dheur, M. C.

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

Dorame, K.

R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
[CrossRef]

El Gawhary, O.

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

Engeln, R.

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

Faber, J.

J. Faber and T. Fawcett, “The powder diffraction file: present and future,” Acta Crystallogr. Sect. B 58, 325–332 (2002).
[CrossRef]

Fawcett, T.

J. Faber and T. Fawcett, “The powder diffraction file: present and future,” Acta Crystallogr. Sect. B 58, 325–332 (2002).
[CrossRef]

Fujiwara, H.

H. Fujiwara, Spectroscopic Ellipsometry: Principles and Applications (Wiley, 2007).

Ge, L.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Hansen, T. A. R.

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

Hendrikx, R. W. A.

Herzinger, C. M.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Hilfiker, J. N.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Hu, B. B.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Jin, Y.

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Johs, B. D.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Kumar, N.

Ma, X. F.

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Morrish, R.

R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
[CrossRef]

Muscat, A.

R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
[CrossRef]

Noh, H.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Olsen, L. C.

L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
[CrossRef]

Papadimitropoulos, G.

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

Pereira, S. F.

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

Planken, P. C. M.

Ramakrishnan, G.

G. Ramakrishnan, G. K. P. Ramanandan, A. J. L. Adam, M. Xu, N. Kumar, R. W. A. Hendrikx, and P. C. M. Planken, “Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals,” Opt. Express 21, 16784–16798 (2013).
[CrossRef]

G. K. P. Ramanandan, G. Ramakrishnan, and P. C. M. Planken, “Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy,” J. Appl. Phys. 111, 123517 (2012).
[CrossRef]

Ramanandan, G. K. P.

G. Ramakrishnan, G. K. P. Ramanandan, A. J. L. Adam, M. Xu, N. Kumar, R. W. A. Hendrikx, and P. C. M. Planken, “Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals,” Opt. Express 21, 16784–16798 (2013).
[CrossRef]

G. K. P. Ramanandan, G. Ramakrishnan, and P. C. M. Planken, “Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy,” J. Appl. Phys. 111, 123517 (2012).
[CrossRef]

Schmidt, M. T.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Stone, A. D.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Synowicki, R. A.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Tham, P.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Urie, M. W.

L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
[CrossRef]

Vamvakas, V. E.

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

Van de Sanden, M. C. M.

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

van der Lingen, E.

C. Cretu and E. van der Lingen, “Coloured gold alloys,” Gold Bull. 32, 115–126 (1999).

van der Valk, N. C. J.

Vourdas, N.

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

Wagoner, G. A.

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Wan, W.

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Wang, W. C.

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Weber, J. W.

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

Wenckebach, T.

Woollam, J. A.

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Xu, M.

Yang, E. S.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Yang, Y. P.

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Zhang, C. L.

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Zhang, L. L.

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Zhang, X.

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Zhang, X. C.

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Zhang, Z. W.

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Acta Crystallogr. Sect. B (1)

J. Faber and T. Fawcett, “The powder diffraction file: present and future,” Acta Crystallogr. Sect. B 58, 325–332 (2002).
[CrossRef]

Appl. Phys. B (1)

O. El Gawhary, M. C. Dheur, S. F. Pereira, and J. J. M. Braat, “Extension of the classical Fabry–Perot formula to 1D multilayered structures,” Appl. Phys. B 111, 637–645 (2013).
[CrossRef]

Appl. Phys. Lett. (3)

L. C. Olsen, R. C. Bohara, and M. W. Urie, “Explanation for low-efficiency Cu2O Schottky-barrier solar cells,” Appl. Phys. Lett. 34, 47–49 (1979).
[CrossRef]

X. Zhang, J. T. Darrow, B. B. Hu, D. H. Auston, M. T. Schmidt, P. Tham, and E. S. Yang, “Optically induced electromagnetic radiation from semiconductor surfaces,” Appl. Phys. Lett. 56, 2228–2230 (1990).
[CrossRef]

Y. Jin, X. F. Ma, G. A. Wagoner, M. Alexander, and X. C. Zhang, “Anomalous optically generated THz beams from metal/GaAs interfaces,” Appl. Phys. Lett. 65, 682–684 (1994).
[CrossRef]

Gold Bull. (1)

C. Cretu and E. van der Lingen, “Coloured gold alloys,” Gold Bull. 32, 115–126 (1999).

J. Appl. Phys. (2)

J. W. Weber, T. A. R. Hansen, M. C. M. Van de Sanden, and R. Engeln, “B-spline parametrization of the dielectric function applied to spectroscopic ellipsometry on amorphous carbon,” J. Appl. Phys. 106, 123503 (2009).
[CrossRef]

G. K. P. Ramanandan, G. Ramakrishnan, and P. C. M. Planken, “Oxidation kinetics of nanoscale copper films studied by terahertz transmission spectroscopy,” J. Appl. Phys. 111, 123517 (2012).
[CrossRef]

J. Opt. Soc. Am. B (1)

J. Phys. (1)

G. Papadimitropoulos, N. Vourdas, V. E. Vamvakas, and D. Davazoglou, “Deposition and characterization of copper oxide thin films,” J. Phys. 10, 182–185 (2005).
[CrossRef]

J. Phys. Chem. C (1)

Y. P. Yang, W. C. Wang, Z. W. Zhang, L. L. Zhang, and C. L. Zhang, “Dielectric and lattice vibrational spectra of Cu2O hollow spheres in the range of 1–10  THz,” J. Phys. Chem. C 115, 10333–10337 (2011).
[CrossRef]

Opt. Express (1)

Proc. SPIE (1)

J. A. Woollam, B. D. Johs, C. M. Herzinger, J. N. Hilfiker, R. A. Synowicki, and C. L. Bungay, “Overview of variable-angle spectroscopic ellipsometry (VASE): I. Basic theory and typical applications,” Proc. SPIE CR75, 3–28 (1999).

Science (1)

W. Wan, Y. Chong, L. Ge, H. Noh, A. D. Stone, and H. Cao, “Time-reversed lasing and interferometric control of absorption,” Science 331, 889–892 (2011).
[CrossRef]

Scr. Mater. (1)

R. Morrish, K. Dorame, and A. Muscat, “Formation of nanoporous Au by dealloying AuCu thin films in HNO3,” Scr. Mater. 64, 856–859 (2011).
[CrossRef]

Other (1)

H. Fujiwara, Spectroscopic Ellipsometry: Principles and Applications (Wiley, 2007).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1.
Fig. 1.

THz generation setup. Ultrafast laser pulses are incident on an 400nm thick Cu2O film deposited on a Au substrate at 45° angle of incidence. Parabolic mirrors are used to collect, collimate, and focus the emitted THz pulses onto a GaP electro-optic crystal. A probe laser beam is also focused onto the GaP crystal. The detector assembly measures the instantaneous THz electric field in the GaP detection crystal as a change in the polarization state of the probe laser beam.

Fig. 2.
Fig. 2.

(a) Time-dependent electric field of the THz pulse emitted from the Au-Cu2O Schottky junction and (b) the corresponding Fourier-transformed spectrum.

Fig. 3.
Fig. 3.

Measured I–V characteristics of the Au/Cu2O junctions. The solid line shows the junction characteristics of a Cu2O thin film fabricated over a Au thin film substrate and the dashed line shows the same when the Au thin film is deposited over the Cu2O thin film. The difference in the junction characteristics between the two cases is explained on the basis of diffusion of Cu into the gold film to form an AuCu alloy in the first case, when the oxide layer is thermally formed on the Au film.

Fig. 4.
Fig. 4.

Photograph of the AuCu alloyed sample surface. The right side of the sample was alloyed and has a slightly different rose-gold color. The left side of the sample is a pure gold surface. The image was processed to obtain a better color contrast.

Fig. 5.
Fig. 5.

XRD measurement of the gold substrates from which oxide was removed. No trace of oxide was found in the substrate.

Fig. 6.
Fig. 6.

Ψ and Δ measurements of the light reflected from a Cu2O thin film on gold substrate (lines). The dots show the values of Ψ and Δ calculated from the model used. Both Ψ and Δ are plotted in units of degrees.

Fig. 7.
Fig. 7.

Frequency-dependent real (n) and imaginary (k) parts of the refractive index of the AuCu interdiffusion layer, the Cu2O thin film, and the Au thin film, as obtained using the VASE software. The inset of (b) gives a closer look at the imaginary part of the refractive index of the Cu2O thin film.

Fig. 8.
Fig. 8.

White light reflection spectra from Cu2O layers of different thicknesses “d” on an AuCu substrate, normalized to the reflection from bare gold substrates. (a) Experimentally measured and (b) calculated from the analytical model using the complex refractive indices of the materials obtained from the ellipsometry analysis. The dashed blue line shows the calculated reflection spectrum of a Cu2O thin film of thickness 223 nm on pure Au.

Equations (1)

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

eiΔtan(Ψ)=ρ=rprs.

Metrics