Abstract

We show that charge carrier mobilities can be measured by reflection time resolved THz spectroscopy (R-TRTS) even for thin films on metal contacts, such as polycrystalline Cu2SnZnSe4 grown on molybdenum. In the measurement a reduced THz reflection upon photo-excitation is observed in contrast to increased THz reflection commonly observed on insulating substrates, and which excludes standard analytic R-TRTS analyses. Instead, a numerical transfer matrix method is used to model the THz reflection from which we derive carrier mobilities of 100 cm2/Vs consistent with literature. We show that R-TRTS on metal substrates is ~100x less sensitive compared to measurements on insulating substrates. These sensitivity of these R-TRTS measurements can be increased by using lower substrate refractive indices, lower substrate conductivities, thicker sample layers or higher THz probe frequencies.

© 2017 Optical Society of America

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    [Crossref]
  2. D. G. Cooke, F. C. Krebs, and P. U. Jepsen, “Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film,” Phys. Rev. Lett. 108(5), 056603 (2012).
    [Crossref] [PubMed]
  3. D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
    [Crossref]
  4. F. D’Angelo, H. Němec, S. H. Parekh, P. Kužel, M. Bonn, and D. Turchinovich, “Self-referenced ultra-broadband transient terahertz spectroscopy using air-photonics,” Opt. Express 24(9), 10157–10171 (2016).
    [Crossref] [PubMed]
  5. C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
    [Crossref]
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    [Crossref]
  8. K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
    [Crossref]
  9. R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
    [Crossref]
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    [Crossref]
  11. M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
    [Crossref]
  12. M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
    [Crossref]
  13. P. Jepsen, D. Cooke, and M. Koch, “Terahertz spectroscopy and imaging - Modern techniques and applications,” Laser Photonics Rev. 5(1), 124–166 (2010).
    [Crossref]
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    [Crossref] [PubMed]
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    [Crossref]
  21. P. Kužel, F. Kadlec, and H. Nĕmec, “Propagation of terahertz pulses in photoexcited media: analytical theory for layered systems,” J. Chem. Phys. 127(2), 024506 (2007).
    [Crossref] [PubMed]
  22. J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
    [Crossref] [PubMed]
  23. S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
    [Crossref]
  24. S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
    [Crossref]
  25. H. Burkhard, H. W. Dinges, and E. Kuphal, “Optical properties of InGaPAs, InP, GaAs, and GaP determined by ellipsometry,” J. Appl. Phys. 53(1), 655–662 (1982).
    [Crossref]
  26. A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
    [Crossref]
  27. G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
    [Crossref]
  28. H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
    [Crossref]
  29. N. Smith, “Classical generalization of the Drude formula for the optical conductivity,” Phys. Rev. B 64(15), 155106 (2001).
    [Crossref]
  30. H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
    [Crossref]

2016 (5)

F. D’Angelo, H. Němec, S. H. Parekh, P. Kužel, M. Bonn, and D. Turchinovich, “Self-referenced ultra-broadband transient terahertz spectroscopy using air-photonics,” Opt. Express 24(9), 10157–10171 (2016).
[Crossref] [PubMed]

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

2015 (1)

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

2014 (3)

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
[Crossref]

2012 (5)

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

D. G. Cooke, F. C. Krebs, and P. U. Jepsen, “Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film,” Phys. Rev. Lett. 108(5), 056603 (2012).
[Crossref] [PubMed]

D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
[Crossref]

K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
[Crossref]

R. Ulbricht, R. Kurstjens, and M. Bonn, “Assessing charge carrier trapping in silicon nanowires using picosecond conductivity measurements,” Nano Lett. 12(7), 3821–3827 (2012).
[Crossref] [PubMed]

2010 (2)

H. Němec, P. Kuzel, and V. Sundström, “Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy,” J. Photochem. Photobiol. Chem. 215(2–3), 123–139 (2010).
[Crossref]

P. Jepsen, D. Cooke, and M. Koch, “Terahertz spectroscopy and imaging - Modern techniques and applications,” Laser Photonics Rev. 5(1), 124–166 (2010).
[Crossref]

2009 (2)

F. D. J. Brunner, A. Schneider, and P. Günter, “A terahertz time-domain spectrometer for simultaneous transmission and reflection measurements at normal incidence,” Opt. Express 17(23), 20684–20693 (2009).
[Crossref] [PubMed]

R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
[Crossref]

2008 (1)

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

2007 (1)

P. Kužel, F. Kadlec, and H. Nĕmec, “Propagation of terahertz pulses in photoexcited media: analytical theory for layered systems,” J. Chem. Phys. 127(2), 024506 (2007).
[Crossref] [PubMed]

2005 (1)

2004 (1)

E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, “Electron transport in TiO 2 probed by THz time-domain spectroscopy,” Phys. Rev. B 69(8), 081101 (2004).
[Crossref]

2002 (1)

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Size-dependent photoconductivity in CdSe nanoparticles as measured by time-resolved terahertz spectroscopy,” Nano Lett. 2(9), 983–987 (2002).
[Crossref]

2001 (3)

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

N. Smith, “Classical generalization of the Drude formula for the optical conductivity,” Phys. Rev. B 64(15), 155106 (2001).
[Crossref]

1982 (1)

H. Burkhard, H. W. Dinges, and E. Kuphal, “Optical properties of InGaPAs, InP, GaAs, and GaP determined by ellipsometry,” J. Appl. Phys. 53(1), 655–662 (1982).
[Crossref]

1965 (1)

J. A. Nelder and R. Mead, “A simplex method for function minimization,” Comput. J. 7(4), 308–313 (1965).
[Crossref]

Abdi, F. F.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

Bartelt, A.

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

Baxter, J. B.

G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
[Crossref]

Beard, M. C.

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Size-dependent photoconductivity in CdSe nanoparticles as measured by time-resolved terahertz spectroscopy,” Nano Lett. 2(9), 983–987 (2002).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

Bonn, M.

F. D’Angelo, H. Němec, S. H. Parekh, P. Kužel, M. Bonn, and D. Turchinovich, “Self-referenced ultra-broadband transient terahertz spectroscopy using air-photonics,” Opt. Express 24(9), 10157–10171 (2016).
[Crossref] [PubMed]

R. Ulbricht, R. Kurstjens, and M. Bonn, “Assessing charge carrier trapping in silicon nanowires using picosecond conductivity measurements,” Nano Lett. 12(7), 3821–3827 (2012).
[Crossref] [PubMed]

E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, “Electron transport in TiO 2 probed by THz time-domain spectroscopy,” Phys. Rev. B 69(8), 081101 (2004).
[Crossref]

Bourdais, S.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

Brunner, F. D. J.

Burkhard, H.

H. Burkhard, H. W. Dinges, and E. Kuphal, “Optical properties of InGaPAs, InP, GaAs, and GaP determined by ellipsometry,” J. Appl. Phys. 53(1), 655–662 (1982).
[Crossref]

Carnahan, M. A.

R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
[Crossref]

Caspar, J. V.

G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
[Crossref]

Chemla, D. S.

R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
[Crossref]

Choi, S. G.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Choudhury, K. R.

G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
[Crossref]

Cooke, D.

P. Jepsen, D. Cooke, and M. Koch, “Terahertz spectroscopy and imaging - Modern techniques and applications,” Laser Photonics Rev. 5(1), 124–166 (2010).
[Crossref]

Cooke, D. G.

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

D. G. Cooke, F. C. Krebs, and P. U. Jepsen, “Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film,” Phys. Rev. Lett. 108(5), 056603 (2012).
[Crossref] [PubMed]

D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
[Crossref]

D’Angelo, F.

Delagnes, J. C.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Dennler, G.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

Dinges, H. W.

H. Burkhard, H. W. Dinges, and E. Kuphal, “Optical properties of InGaPAs, InP, GaAs, and GaP determined by ellipsometry,” J. Appl. Phys. 53(1), 655–662 (1982).
[Crossref]

Dolotko, O.

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

Donohue, A. L.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Eichberger, R.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

Fekete, L.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Fischer, B. M.

Fischer, S. F.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Friedrich, D.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

Gokmen, T.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Guglietta, G. W.

G. W. Guglietta, K. R. Choudhury, J. V. Caspar, and J. B. Baxter, “Employing time-resolved terahertz spectroscopy to analyze carrier dynamics in thin-film Cu2ZnSn(S,Se)4 absorber layers,” Appl. Phys. Lett. 104(25), 253901 (2014).
[Crossref]

Gunawan, O.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Günter, P.

Hägele, D.

R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
[Crossref]

Handwerg, M.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Heinz, T. F.

E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, “Electron transport in TiO 2 probed by THz time-domain spectroscopy,” Phys. Rev. B 69(8), 081101 (2004).
[Crossref]

Hempel, H.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Hendry, E.

E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, “Electron transport in TiO 2 probed by THz time-domain spectroscopy,” Phys. Rev. B 69(8), 081101 (2004).
[Crossref]

Hiroi, H.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Hopstaken, M.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Itoh, T.

K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
[Crossref]

Jacob, A.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

Jepsen, P.

P. Jepsen, D. Cooke, and M. Koch, “Terahertz spectroscopy and imaging - Modern techniques and applications,” Laser Photonics Rev. 5(1), 124–166 (2010).
[Crossref]

Jepsen, P. U.

D. G. Cooke, F. C. Krebs, and P. U. Jepsen, “Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film,” Phys. Rev. Lett. 108(5), 056603 (2012).
[Crossref] [PubMed]

P. U. Jepsen and B. M. Fischer, “Dynamic range in terahertz time-domain transmission and reflection spectroscopy,” Opt. Lett. 30(1), 29–31 (2005).
[Crossref] [PubMed]

Just, J.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

Kadlec, F.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

P. Kužel, F. Kadlec, and H. Nĕmec, “Propagation of terahertz pulses in photoexcited media: analytical theory for layered systems,” J. Chem. Phys. 127(2), 024506 (2007).
[Crossref] [PubMed]

Kaindl, R. A.

R. A. Kaindl, D. Hägele, M. A. Carnahan, and D. S. Chemla, “Transient terahertz spectroscopy of excitons and unbound carriers in quasi-two-dimensional electron-hole gases,” Phys. Rev. B 79(4), 045320 (2009).
[Crossref]

Kanatzidis, M. G.

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

Kasap, S. O.

K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
[Crossref]

Kaufmann, C.

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

Kim, J.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Koch, M.

P. Jepsen, D. Cooke, and M. Koch, “Terahertz spectroscopy and imaging - Modern techniques and applications,” Laser Photonics Rev. 5(1), 124–166 (2010).
[Crossref]

Krebs, F. C.

D. G. Cooke, F. C. Krebs, and P. U. Jepsen, “Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film,” Phys. Rev. Lett. 108(5), 056603 (2012).
[Crossref] [PubMed]

Kuphal, E.

H. Burkhard, H. W. Dinges, and E. Kuphal, “Optical properties of InGaPAs, InP, GaAs, and GaP determined by ellipsometry,” J. Appl. Phys. 53(1), 655–662 (1982).
[Crossref]

Kurstjens, R.

R. Ulbricht, R. Kurstjens, and M. Bonn, “Assessing charge carrier trapping in silicon nanowires using picosecond conductivity measurements,” Nano Lett. 12(7), 3821–3827 (2012).
[Crossref] [PubMed]

Kuwahara, M.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Kuzel, P.

H. Němec, P. Kuzel, and V. Sundström, “Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy,” J. Photochem. Photobiol. Chem. 215(2–3), 123–139 (2010).
[Crossref]

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Kužel, P.

F. D’Angelo, H. Němec, S. H. Parekh, P. Kužel, M. Bonn, and D. Turchinovich, “Self-referenced ultra-broadband transient terahertz spectroscopy using air-photonics,” Opt. Express 24(9), 10157–10171 (2016).
[Crossref] [PubMed]

P. Kužel, F. Kadlec, and H. Nĕmec, “Propagation of terahertz pulses in photoexcited media: analytical theory for layered systems,” J. Chem. Phys. 127(2), 024506 (2007).
[Crossref] [PubMed]

Larramona, G.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Lee, Y. S.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Lerch, M.

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

Levcenko, S.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

Li, J.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Mangeney, J.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Martin, M.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Mead, R.

J. A. Nelder and R. Mead, “A simplex method for function minimization,” Comput. J. 7(4), 308–313 (1965).
[Crossref]

Meldrum, A.

D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
[Crossref]

Mitzi, D. B.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Moisan, C.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Mounaix, P.

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

Müller, S.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

Nair, D.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Naito, H.

K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
[Crossref]

Nelder, J. A.

J. A. Nelder and R. Mead, “A simplex method for function minimization,” Comput. J. 7(4), 308–313 (1965).
[Crossref]

Nemec, H.

F. D’Angelo, H. Němec, S. H. Parekh, P. Kužel, M. Bonn, and D. Turchinovich, “Self-referenced ultra-broadband transient terahertz spectroscopy using air-photonics,” Opt. Express 24(9), 10157–10171 (2016).
[Crossref] [PubMed]

H. Němec, P. Kuzel, and V. Sundström, “Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy,” J. Photochem. Photobiol. Chem. 215(2–3), 123–139 (2010).
[Crossref]

H. Němec, L. Fekete, F. Kadlec, P. Kuzel, M. Martin, J. Mangeney, J. C. Delagnes, and P. Mounaix, “Ultrafast carrier dynamics in Br + -bombarded InP studied by time-resolved terahertz spectroscopy,” Phys. Rev. B 78(23), 235206 (2008).
[Crossref]

P. Kužel, F. Kadlec, and H. Nĕmec, “Propagation of terahertz pulses in photoexcited media: analytical theory for layered systems,” J. Chem. Phys. 127(2), 024506 (2007).
[Crossref] [PubMed]

Norman, A. G.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Parekh, S. H.

Perkins, C. L.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Persson, C.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Ponseca, C. S.

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

Redinger, A.

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Repins, I.

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

Repins, I. L.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Ritscher, A.

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

Schmuttenmaer, C. A.

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Size-dependent photoconductivity in CdSe nanoparticles as measured by time-resolved terahertz spectroscopy,” Nano Lett. 2(9), 983–987 (2002).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

Schneider, A.

Schorr, S.

A. Ritscher, J. Just, O. Dolotko, S. Schorr, and M. Lerch, “A mechanochemical route to single phase Cu2ZnSnS4 powder,” J. Alloys Compd. 670, 289–296 (2016).
[Crossref]

Shan, J.

E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, “Electron transport in TiO 2 probed by THz time-domain spectroscopy,” Phys. Rev. B 69(8), 081101 (2004).
[Crossref]

Shimakawa, K.

K. Shimakawa, T. Itoh, H. Naito, and S. O. Kasap, “The origin of non-Drude terahertz conductivity in nanomaterials,” Appl. Phys. Lett. 100(13), 132102 (2012).
[Crossref]

Shin, B.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Smith, N.

N. Smith, “Classical generalization of the Drude formula for the optical conductivity,” Phys. Rev. B 64(15), 155106 (2001).
[Crossref]

Stoumpos, C. C.

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

Strothkämper, C.

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

Sugimoto, H.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Sundström, V.

D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
[Crossref]

H. Němec, P. Kuzel, and V. Sundström, “Charge transport in nanostructured materials for solar energy conversion studied by time-resolved terahertz spectroscopy,” J. Photochem. Photobiol. Chem. 215(2–3), 123–139 (2010).
[Crossref]

To, B.

S. G. Choi, H. Y. Zhao, C. Persson, C. L. Perkins, A. L. Donohue, B. To, A. G. Norman, J. Li, and I. L. Repins, “Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV,” J. Appl. Phys. 111(3), 033506 (2012).
[Crossref]

Todorov, T. K.

J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
[Crossref] [PubMed]

Turchinovich, D.

Turner, G. M.

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Size-dependent photoconductivity in CdSe nanoparticles as measured by time-resolved terahertz spectroscopy,” Nano Lett. 2(9), 983–987 (2002).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Subpicosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved terahertz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001).
[Crossref]

Uhd Jepsen, P.

D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
[Crossref]

Ulbricht, R.

R. Ulbricht, R. Kurstjens, and M. Bonn, “Assessing charge carrier trapping in silicon nanowires using picosecond conductivity measurements,” Nano Lett. 12(7), 3821–3827 (2012).
[Crossref] [PubMed]

Unold, T.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

S. Levcenko, J. Just, A. Redinger, G. Larramona, S. Bourdais, G. Dennler, A. Jacob, and T. Unold, “Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content,” Phys. Rev. Appl. 5(2), 024004 (2016).
[Crossref]

H. Hempel, A. Redinger, I. Repins, C. Moisan, G. Larramona, G. Dennler, M. Handwerg, S. F. Fischer, R. Eichberger, and T. Unold, “Intragrain charge transport in kesterite thin films - Limits arising from carrier localization,” J. Appl. Phys. 120(17), 175302 (2016).
[Crossref]

C. Strothkämper, A. Bartelt, R. Eichberger, C. Kaufmann, and T. Unold, “Microscopic mobilities and cooling dynamics of photoexcited carriers in polycrystalline CuInSe2,” Phys. Rev. B 89(11), 115204 (2014).
[Crossref]

Valverde-Chavez, D. A.

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van de Krol, R.

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
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D. A. Valverde-Chavez, C. S. Ponseca, C. C. Stoumpos, A. Yartsev, M. G. Kanatzidis, V. Sundström, and D. G. Cooke, “Intrinsic femtosecond charge generation dynamics in single crystal H3NH3PbI3,” Energy Environ. Sci. 8(12), 3700–3707 (2015).
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M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

ACS Energy Lett. (1)

M. Ziwritsch, S. Müller, H. Hempel, T. Unold, F. F. Abdi, R. van de Krol, D. Friedrich, and R. Eichberger, “Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4,” ACS Energy Lett. 1(5), 888–894 (2016).
[Crossref]

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J. Kim, H. Hiroi, T. K. Todorov, O. Gunawan, M. Kuwahara, T. Gokmen, D. Nair, M. Hopstaken, B. Shin, Y. S. Lee, W. Wang, H. Sugimoto, and D. B. Mitzi, “High efficiency Cu2ZnSn(S,Se)4 solar cells by applying a double In2S3/CdS emitter,” Adv. Mater. 26(44), 7427–7431 (2014).
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D. G. Cooke, A. Meldrum, and P. Uhd Jepsen, “Ultrabroadband terahertz conductivity of Si nanocrystal films,” Appl. Phys. Lett. 101(21), 211107 (2012).
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F. Ladouceur and J. D. Love, Silica-Based Buried Channel Waveguides and Devices (Chapman & Hall, 1995)

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Figures (7)

Fig. 1
Fig. 1 Convertible reflection and transmission time resolved THz spectroscopy setup. The optical elements are: DL: delay line, CH: chopper, BS: THz beam splitter, M: mirror.
Fig. 2
Fig. 2 Complex refractive index in the THz regime of a Mo substrate compared to typical substrate materials with low conductivity measured by transmission time domain THz spectroscopy. The refractive index of Mo is one order higher, frequency dependent and strongly absorbing (imaginary) which is caused by its high conductivity (Eq. (2)) and will affect the R-TRTS signal and analysis.
Fig. 3
Fig. 3 Comparison of R-TRTS signals for semiconductor thin films on metal (Mo) and low conductive (glass) substrates. Small negative R-TRTS signal for Cu2SnZnSe4 thin film on a Mo substrate (magnified by x20) compared to a positive R-TRTS signal on a glass.
Fig. 4
Fig. 4 Transfer matrix modeled R-TRTS signal for a thin film (d = 1.9 µm; n = 2.7, f = 1 THz, F = 4*1012cm−2; µ = 100 cm2/Vs; α = 4.4*104 cm−1) as function of the substrate refractive index modelled numerically and by Eq. (1). Equation (1) is only valid for substrates with similar refractive index as the probed thin film (2.7). Amplitude of the modeled R-TRTS signal decreases and the photo induced THz reflection becomes negative with increasing substrate reflective index which reproduces the observations for glass (n = 2.55) and Mo (n ~75) in Fig. 3.
Fig. 5
Fig. 5 R-TRTS signal ΔR/R depending on film thickness d and mobility µ modelled for a thin film (n = 2.7, α = 4.4*104 cm−1, f = 1 THz) on a metal substrate (n = 75 + 75i) for 0.15 W pump power (4*1012 photon/cm2 at 150 kHz). Resolution limits of a typical R-TRTS setup are indicated for different measurement times.
Fig. 6
Fig. 6 Agreement of the charge carrier mobility for Cu2ZnSnSe4 thin films on Mo and glass proves reliable numerical R-TRTS analysis on metal substrates.
Fig. 7
Fig. 7 Real and imaginary part of the charge carrier mobility for an InP wafer retrieved from the R-TRTS data in Fig. 3. The mobility calculated by Eq. (1) as well as by the numerical transfer matrix method agree and are modelled by the Drude model with an effective mass of 0.095 and a momentum relaxation time of 117 fs.

Equations (2)

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μ e Δ N = ε 0 c α ( n 2 1 ) 2 ( 1 2 i ω n α c ) Δ R R n 1 2 Δ R ε 0 c α ( n 2 1 ) 2 Δ R R
n 2 = n s t 2 + i σ ω ε 0

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