Abstract

Indium oxide (In2O3) films grown by thermal oxidation on MgO substrates were optically excited by femtosecond laser pulses having photon energy lower than the In2O3 bandgap. Terahertz (THz) pulse emission was observed using time domain spectroscopy. Results show that THz emission saturates at an excitation fluence of ~400 nJ/cm2. Even as two-photon absorption has been excluded, the actual emission mechanism has yet to be confirmed but is currently attributed to carriers due to weak absorption from defect levels that are driven by a strain field at the interface of the substrate and the grown film.

© 2012 OSA

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    [CrossRef]
  3. S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
    [CrossRef]
  4. M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
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    [CrossRef]
  7. G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).
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    [CrossRef]
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    [CrossRef]
  10. P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
  22. J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
    [CrossRef]
  23. T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
    [CrossRef]
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    [CrossRef]
  25. A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
    [CrossRef] [PubMed]
  26. E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
    [CrossRef]
  27. K. Hess, Advanced Theory of Semiconductor Devices (Wiley Interscience, 2000).

2010 (1)

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

2009 (5)

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
[CrossRef] [PubMed]

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

2008 (3)

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

V. L. Malevich, R. Adomavičius, and A. Krotkus, “THz emission from semiconductor surfaces,” C. R. Phys. 9(2), 130–141 (2008).
[CrossRef]

2007 (1)

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

2006 (1)

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

2005 (3)

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

2004 (2)

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

2003 (2)

J. F. Holzman and A. Y. Elezzabi, “Two-photon photoconductive terahertz generation in ZnSe,” Appl. Phys. Lett. 83(14), 2967–2969 (2003).
[CrossRef]

C. Soci and D. Moses, “Terahertz generation from poly(p-phenylene vinylene) photoconductive antenna,” Synth. Met. 139(3), 815–817 (2003).
[CrossRef]

2000 (1)

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

1998 (1)

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

1997 (1)

H. Sieber, St. Senz, and D. Hesse, “Crystallographic orientation and morphology of epitaxial In2O3 thin films grown on MgO(001) single crystal substrates,” Thin Solid Films 303(1–2), 216–221 (1997).

1996 (1)

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

1995 (1)

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

1991 (1)

B. B. Hu, X.-C. Zhang, and D. H. Auston, “Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs,” Phys. Rev. Lett. 67(19), 2709–2712 (1991).
[CrossRef] [PubMed]

1966 (1)

R. L. Weiher and R. P. Ley, “Optical properties of indium oxide,” J. Appl. Phys. 37(1), 299–302 (1966).
[CrossRef]

Adomavicius, R.

V. L. Malevich, R. Adomavičius, and A. Krotkus, “THz emission from semiconductor surfaces,” C. R. Phys. 9(2), 130–141 (2008).
[CrossRef]

Albe, K.

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

Almaral, A.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Alves, E.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Ambacher, O.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Ascázubi, R.

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

Auston, D. H.

B. B. Hu, X.-C. Zhang, and D. H. Auston, “Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs,” Phys. Rev. Lett. 67(19), 2709–2712 (1991).
[CrossRef] [PubMed]

Awitan, F. C. B.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Bechstedt, F.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Bell, G. R.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Bourlange, A.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

Cadatal-Raduban, M.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Carrig, T. J.

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

Chandrashekhar, M.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Choi, W. C.

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

Cimalla, V.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Clement, T. S.

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

Conde, O.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Dawlaty, J.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Defensor, M.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Denniston, K.

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

Diwa, G.

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Donchev, I.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Egdell, R.

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

Egdell, R. G.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Elezzabi, A. Y.

J. F. Holzman and A. Y. Elezzabi, “Two-photon photoconductive terahertz generation in ZnSe,” Appl. Phys. Lett. 83(14), 2967–2969 (2003).
[CrossRef]

Erhart, P.

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

Estacio, E.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

Fortunato, E.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Fuchs, F.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Fuks, D.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Fukuda, T.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Garcia, A.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

George, P. A.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Girtan, M.

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

Golovanov, V.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Gurlui, S.

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

Han, S.-H.

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

Hangyo, M.

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

Hesse, D.

H. Sieber, St. Senz, and D. Hesse, “Crystallographic orientation and morphology of epitaxial In2O3 thin films grown on MgO(001) single crystal substrates,” Thin Solid Films 303(1–2), 216–221 (1997).

Holzman, J. F.

J. F. Holzman and A. Y. Elezzabi, “Two-photon photoconductive terahertz generation in ZnSe,” Appl. Phys. Lett. 83(14), 2967–2969 (2003).
[CrossRef]

Hu, B. B.

B. B. Hu, X.-C. Zhang, and D. H. Auston, “Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs,” Phys. Rev. Lett. 67(19), 2709–2712 (1991).
[CrossRef] [PubMed]

Ichikawa, Y.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Ivanovskaya, M.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Izumida, S.

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

Jaculbia, R. B.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Kapse, H. N.

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

Kim, C. K.

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

Kim, E. K.

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

King, P.

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

King, P. D. C.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Kiv, A.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Klein, A.

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

Krotkus, A.

V. L. Malevich, R. Adomavičius, and A. Krotkus, “THz emission from semiconductor surfaces,” C. R. Phys. 9(2), 130–141 (2008).
[CrossRef]

Kumar, M.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Lakshmi, K. V.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Lavareda, G.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Lee, M. S.

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

Ley, R. P.

R. L. Weiher and R. P. Ley, “Optical properties of indium oxide,” J. Appl. Phys. 37(1), 299–302 (1966).
[CrossRef]

Liu, C. C.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Liu, Z.

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

Lu, H.

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

Makhija, K. K.

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

Malevich, V. L.

V. L. Malevich, R. Adomavičius, and A. Krotkus, “THz emission from semiconductor surfaces,” C. R. Phys. 9(2), 130–141 (2008).
[CrossRef]

Mane, R. S.

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

McConville, C.

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

McConville, C. F.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Mehta, B. R.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Min, S.-K.

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

Moses, D.

C. Soci and D. Moses, “Terahertz generation from poly(p-phenylene vinylene) photoconductive antenna,” Synth. Met. 139(3), 815–817 (2003).
[CrossRef]

Murakami, H.

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Nagasaka, R.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Nakajima, M.

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

Nakazato, T.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Nunes de Carvalho, C.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Ogino, H.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Ohshima, E.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Ohtake, H.

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

Ono, S.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

Othonos, A.

A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
[CrossRef] [PubMed]

Patel, R. M.

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

Payne, D.

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

Payne, D. J.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Pham, M. H.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Pobre, R.

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

Quema, A.

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Ramos, A. R.

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Rana, F.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Ray, A.

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

Rodriguez, G.

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

Rusu, G. G.

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

Rusu, G. I.

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

Salvador, A.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Sarukura, N.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

Schaff, W. J.

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

Senz, St.

H. Sieber, St. Senz, and D. Hesse, “Crystallographic orientation and morphology of epitaxial In2O3 thin films grown on MgO(001) single crystal substrates,” Thin Solid Films 303(1–2), 216–221 (1997).

Sharma, R.

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

Shimizu, T.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Shivaraman, S.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Sieber, H.

H. Sieber, St. Senz, and D. Hesse, “Crystallographic orientation and morphology of epitaxial In2O3 thin films grown on MgO(001) single crystal substrates,” Thin Solid Films 303(1–2), 216–221 (1997).

Singh, F.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Singh, J. P.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Singh, V. N.

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

Smatko, V.

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

Soci, C.

C. Soci and D. Moses, “Terahertz generation from poly(p-phenylene vinylene) photoconductive antenna,” Synth. Met. 139(3), 815–817 (2003).
[CrossRef]

Somintac, A.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Spencer, M. G.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Stewart, K. R.

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

Strait, J. H.

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

Takatori, S.

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Tani, M.

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

Taylor, A. J.

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

Trivedi, U. B.

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

Tsokkou, D.

A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
[CrossRef] [PubMed]

Uchida, K.

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

Veal, T.

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

Veal, T. D.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Wang, Ch. Y.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Weiher, R. L.

R. L. Weiher and R. P. Ley, “Optical properties of indium oxide,” J. Appl. Phys. 37(1), 299–302 (1966).
[CrossRef]

Wilke, I.

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

Yoshikawa, A.

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

Zervos, M.

A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
[CrossRef] [PubMed]

Zhang, H.

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Zhang, X.-C.

B. B. Hu, X.-C. Zhang, and D. H. Auston, “Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs,” Phys. Rev. Lett. 67(19), 2709–2712 (1991).
[CrossRef] [PubMed]

Appl. Phys. Lett. (9)

G. Diwa, A. Quema, E. Estacio, R. Pobre, H. Murakami, S. Ono, and N. Sarukura, “Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling,” Appl. Phys. Lett. 87(15), 151114 (2005).
[CrossRef]

S. Ono, H. Murakami, A. Quema, G. Diwa, N. Sarukura, R. Nagasaka, Y. Ichikawa, H. Ogino, E. Ohshima, A. Yoshikawa, and T. Fukuda, “Generation of terahertz radiation using zinc oxide as photoconductive material excited by ultraviolet pulses,” Appl. Phys. Lett. 87(26), 261112 (2005).
[CrossRef]

R. Ascázubi, I. Wilke, K. Denniston, H. Lu, and W. J. Schaff, “Terahertz emission by InN,” Appl. Phys. Lett. 84(23), 4810–4812 (2004).
[CrossRef]

M. Nakajima, K. Uchida, M. Tani, and M. Hangyo, “Strong enhancement of terahertz radiation from semiconductor surfaces using MgO hemispherical lens coupler,” Appl. Phys. Lett. 85(2), 191–193 (2004).
[CrossRef]

J. F. Holzman and A. Y. Elezzabi, “Two-photon photoconductive terahertz generation in ZnSe,” Appl. Phys. Lett. 83(14), 2967–2969 (2003).
[CrossRef]

J. H. Strait, P. A. George, J. Dawlaty, S. Shivaraman, M. Chandrashekhar, F. Rana, and M. G. Spencer, “Emission of terahertz radiation from SiC,” Appl. Phys. Lett. 95(5), 051912 (2009).
[CrossRef]

T. J. Carrig, G. Rodriguez, T. S. Clement, A. J. Taylor, and K. R. Stewart, “Scaling of terahertz radiation via optical rectification in electro-optic crystals,” Appl. Phys. Lett. 66(2), 121–123 (1995).
[CrossRef]

M. Kumar, V. N. Singh, F. Singh, K. V. Lakshmi, B. R. Mehta, and J. P. Singh, “On the origin of photoluminescence in indium oxide octahedron structures,” Appl. Phys. Lett. 92(17), 171907 (2008).
[CrossRef]

E. Estacio, M. H. Pham, S. Takatori, M. Cadatal-Raduban, T. Nakazato, T. Shimizu, N. Sarukura, A. Somintac, M. Defensor, F. C. B. Awitan, R. B. Jaculbia, A. Salvador, and A. Garcia, “Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures,” Appl. Phys. Lett. 94(23), 232104 (2009).
[CrossRef]

Appl. Surf. Sci. (1)

M. Girtan, G. I. Rusu, G. G. Rusu, and S. Gurlui, “Influence of oxidation conditions on the properties of indium oxide thin films,” Appl. Surf. Sci. 162–163, 492–498 (2000).
[CrossRef]

Bull. Mater. Sci. (1)

K. K. Makhija, A. Ray, R. M. Patel, U. B. Trivedi, and H. N. Kapse, “Indium oxide thin film based ammonia gas and ethanol vapour sensor,” Bull. Mater. Sci. 28(1), 9–17 (2005).
[CrossRef]

C. R. Phys. (1)

V. L. Malevich, R. Adomavičius, and A. Krotkus, “THz emission from semiconductor surfaces,” C. R. Phys. 9(2), 130–141 (2008).
[CrossRef]

Compound Semicon. (1)

T. Veal, P. King, C. McConville, D. Payne, A. Bourlange, and R. Egdell, “Transparent oxides: MBE unmasks the real indium oxide,” Compound Semicon. 14(11), 27 (2008).

J. Alloy. Comp. (1)

R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, “Optimization of growth on In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells,” J. Alloy. Comp. 479(1–2), 840–843 (2009).
[CrossRef]

J. Appl. Phys. (2)

R. L. Weiher and R. P. Ley, “Optical properties of indium oxide,” J. Appl. Phys. 37(1), 299–302 (1966).
[CrossRef]

N. Sarukura, H. Ohtake, S. Izumida, and Z. Liu, “High average-power THz radiation from femtosecond laser-irradiated InAs in a magnetic field and its elliptical polarization characteristics,” J. Appl. Phys. 84(1), 654–656 (1998).
[CrossRef]

J. Mater. Sci. Mater. Electron. (1)

V. Smatko, V. Golovanov, C. C. Liu, A. Kiv, D. Fuks, I. Donchev, and M. Ivanovskaya, “Structural stability of In2O3 films as sensor materials,” J. Mater. Sci. Mater. Electron. 21(4), 360–363 (2010).
[CrossRef]

J. Non-Cryst. Solids (1)

G. Lavareda, C. Nunes de Carvalho, E. Fortunato, A. R. Ramos, E. Alves, O. Conde, and A. Almaral, “Transparent thin film transistors based on indium oxide semiconductor,” J. Non-Cryst. Solids 352(23–25), 2311–2314 (2006).

Nanoscale Res. Lett. (1)

A. Othonos, M. Zervos, and D. Tsokkou, “Femtosecond carrier dynamics in In2O3 nanocrystals,” Nanoscale Res. Lett. 4(6), 526–531 (2009).
[CrossRef] [PubMed]

Phys. Rev. B (2)

P. Erhart, A. Klein, R. Egdell, and K. Albe, “Band structure of indium oxide: Indirect versus direct band gap,” Phys. Rev. B 75(15), 153205 (2007).
[CrossRef]

P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, and C. F. McConville, “Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3,” Phys. Rev. B 79(20), 205211 (2009).
[CrossRef]

Phys. Rev. Lett. (1)

B. B. Hu, X.-C. Zhang, and D. H. Auston, “Terahertz radiation induced by subband-gap femtosecond optical excitation of GaAs,” Phys. Rev. Lett. 67(19), 2709–2712 (1991).
[CrossRef] [PubMed]

Synth. Met. (1)

C. Soci and D. Moses, “Terahertz generation from poly(p-phenylene vinylene) photoconductive antenna,” Synth. Met. 139(3), 815–817 (2003).
[CrossRef]

Thin Solid Films (2)

H. Sieber, St. Senz, and D. Hesse, “Crystallographic orientation and morphology of epitaxial In2O3 thin films grown on MgO(001) single crystal substrates,” Thin Solid Films 303(1–2), 216–221 (1997).

M. S. Lee, W. C. Choi, E. K. Kim, C. K. Kim, and S.-K. Min, “Characterization of the oxidized indium thin films with thermal oxidation,” Thin Solid Films 279(1–2), 1–3 (1996).

Other (2)

P. Gu and M. Tani, “Terahertz radiation from semiconductor surfaces,” in Terahertz Optoelectronics: Topics in Applied Physics, Vol. 97, K. Sakai, ed. (Springer-Verlag, 2005).

K. Hess, Advanced Theory of Semiconductor Devices (Wiley Interscience, 2000).

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Figures (4)

Fig. 1
Fig. 1

(a) SEM images of the In2O3/MgO films that were oxidized at different temperatures. The films are characterized by grain-like structures. (b) XRD data showing the polycrystalline nature of the films. The most intense peak is attributed to the MgO substrate while the rest are assigned to cubic-In2O3 structure. Results show that incomplete oxidation occurred due to the presence of a diffraction peak assigned to Indium metal.

Fig. 2
Fig. 2

THz-TDS plots for the In2O3/MgO films oxidized at 350°C, 450°C, 550°C. The sample oxidized at 450°C exhibited the most intense THz emission. The inset shows the corresponding Fourier-transform spectra of the TDS data. The THz emission is centered at ~1 THz, and having frequency components of up to 2 THz. A signal-to-noise ratio dynamic range of more than 1 order of magnitude for the 450°C-oxidized sample illustrates implies intense THz emission.

Fig. 3
Fig. 3

Excitation fluence dependence of the THz emission from the 450°C-oxidized sample. The slope of the log-log plot indicates that the THz radiation mechanism is not a nonlinear optical process. The inset compares the THz emission from below-bandgap and above-bandgap excitation showing that the 800 nm wavelength pump is more efficient (the traces have been offset for ease of comparison); thereby ruling out a two-photon absorption process as the origin of the photo-carriers causing THz emission.

Fig. 4
Fig. 4

In the transmission-type excitation geometry, the THz emission intensity does not vary much whether the sample was excited from the MgO substrate side or from the In2O3 film side. Even as the sample’s over-all optical transmission is relatively low due to strong scattering, its THz optical qualities are not compromised. The TDS waveforms have been shifted for ease of comparison.

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