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The sensitive control of semiconductor properties of non-vacuum and electrochemically synthesized CdTe thin films

  • T. M. Demiriz
  • Ahmet PeksozEmail author
Article
  • 13 Downloads

Abstract

CdTe thin films are deposited on indium tin oxide (ITO) coated glass substrates by co-electrochemical deposition method. CdTe films are deposited at six different deposition potentials such as − 0.4, − 0.5, − 0.6, − 0.7, − 0.8 and − 0.9 V versus Ag/AgCl reference electrode. Deposition time is kept constant for 2 min. Deposition electrolyte includes aqueous solutions of 10 mM CdCl2, 20 mM Na2TeO3 as precursors, and 200 mM LiCl. HCl is used for pH adjustment of the electrolyte. The effect of deposition potential on the characteristics of CdTe thin films is investigated by means of some techniques such as scanning electron microscopy (SEM), energy dispersive X-rays analysis (EDX), X-ray diffraction (XRD), Ultraviolet–Visible (UV–Vis) spectroscopy, Mott-Schottky measurements, and electrochemical impedance spectroscopy (EIS). Deposition potential dependency of the film surfaces is seen to be high from the SEM studies. EDX results show that Cd/Te ratios vary between 0.81 and 1.09. XRD analyses show that the films include hexagonal phase of CdTe and Cd1.81Te, and monoclinic phase of CdTe2O5. The optical band gaps (Eg) of all the films are derived from Tauc’s relation using absorbance data. Eg values change between 1.54 and 1.92 eV depending on the deposition voltage. Donor density of the n-type CdTe thin films deposited in the potential range between − 0.4 and − 0.8 V changes between ~ 1017 and ~ 1019 cm−3, while acceptor density is ~ 1020 cm−3 for only one p-type CdTe thin film with a deposition potential of − 0.9 V. Electronic energy band structure of the synthesized CdTe thin films are also studied in detail. From the equivalent electronic circuit fitted to the EIS data, electronic charge transfer in the CdTe/electrolyte system is determined to be the biggest for the CdTe film deposited at − 0.5 V.

Notes

Acknowledgements

This work was supported by the Research Fund of the Uludag University, Project Number KUAP(F)–2015/63. The authors thank to Uludag University for financial support.

References

  1. 1.
    K. Chi, Q. Li, X. Meng, L. Liu, D. Ding, H. Yang, W. Fu, Morphological control and characterization of CdTe microstructure arrays synthesized by one-step electrodeposition. Mater. Lett. 194, 78–80 (2017)CrossRefGoogle Scholar
  2. 2.
    O. Razmjoo, M.E. Bahrololoom, P. Najafisayar, The effect of current density on the composition, structure, morphology and optical properties of galvanostatically electrodeposited nanostructured cadmium telluride films. Ceram. Int. 43, 121–127 (2017)CrossRefGoogle Scholar
  3. 3.
    Q. Li, L. Tian, K. Chi, H. Yang, M. Sun, W. Fu, Electrochemical growth and characterization of CdTe nanorod arrays. Appl. Surf. Sci. 270, 707–711 (2013)CrossRefGoogle Scholar
  4. 4.
    A.A. Ojo, H.I. Salim, O.I. Olusola, M.L. Madugu, I.M. Dharmadasa, Effect of thickness: a case study of electrodeposited CdS in CdS/CdTe based photovoltaic devices. J. Mater. Sci.: Mater. Electron. 28, 3254–3263 (2017)Google Scholar
  5. 5.
    B. Shan, W. Wu, K. Feng, H. Nan, Electrodeposition of wurtzite CdTe and the potential dependence of the phase structure. Mater. Lett. 166, 85–88 (2016)CrossRefGoogle Scholar
  6. 6.
    O.I. Olusola, M.L. Madugu, I.M. Dharmadasa, Investigating the electronic properties of multi-junction ZnS/CdS/CdTe graded bandgap solar cells. Mater. Chem. Phys. 191, 145–150 (2017)CrossRefGoogle Scholar
  7. 7.
    I.M. Dharmadasa, M.L. Madugu, O.I. Olusola, O.K. Echendu, F. Fauzi, D.G. Diso, A.R. Weerasinghe, T. Druffel, R. Dharmadasa, B. Lavery, J.B. Jasinski, T.A. Krentsel, G. Sumanasekera, Electroplating of CdTe thin films from cadmium sulphate precursor and comparison of layers grown by 3-electrode and 2-electrode systems. Coatings 7(2), 1–17 (2017)CrossRefGoogle Scholar
  8. 8.
    H. Gómez, R. Henríquez, R. Schrebler, R. Córdova, D. Ramírez, G. Riveros, E.A. Dalchiele, Electrodeposition of CdTe thin films onto n-Si(1 0 0): nucleation and growth mechanisms. Electrochim. Acta 50(3), 1299–1305 (2005)CrossRefGoogle Scholar
  9. 9.
    I.M. Dharmadasa, O.K. Echendu, F. Fauzi, N.A. Abdul-Manaf, H.I. Salim, T. Druffel, R. Dharmadasa, B. Lavery, Effects of CdCl2 treatment on deep levels in CdTe and their implications on thin film solar cells: a comprehensive photoluminescence study. J. Mater. Sci.: Mater. Electron. 26, 4571–4583 (2015)Google Scholar
  10. 10.
    O.K. Echendu, I.M. Dharmadasa, Graded-bandgap solar cells using all-electrodeposited ZnS, CdS and CdTe thin-films. Energies 8, 4416–4435 (2015)CrossRefGoogle Scholar
  11. 11.
    A.A. Ojo, I.M. Dharmadasa, The effect of fluorine doping on the characteristic behaviour of CdTe. J. Electron. Mater. 45(11), 5728–5738 (2016)CrossRefGoogle Scholar
  12. 12.
    Y.E. Firat, A. Peksoz, Electrochemical synthesis of polyaniline/inorganic salt binary nanofiber thin films for electrochromic applications. J. Mater. Sci. Mater. Electron. 28, 3515–3522 (2017)CrossRefGoogle Scholar
  13. 13.
    J. Tauc, R. Grigorovici, A. Vancu, Optical properties and electronic structure of amorphous germanium. Phys. Stat. Sol. 15, 627–637 (1966)CrossRefGoogle Scholar
  14. 14.
    Y.E. Firat, H. Yildirim, K. Erturk, A. Peksoz, Ultrasonic spray pyrolysis deposited copper sulphide thin films for solar cell applications. Scanning 2017 1–8 (2017)CrossRefGoogle Scholar
  15. 15.
    R. van de Krol, A. Goossens, J. Schoonman, Mott-Schottky analysis of nanometer-scale thin-film anatase TiO2. J. Electrochem. Soc. 144, 1723–1727 (1997)CrossRefGoogle Scholar
  16. 16.
    I. Strzalkowski, S. Joshi, C.R. Crowell, Dielectric constant and its temperature dependence for GaAs, CdTe, and ZnSe. Appl. Phys. Lett. 28, 350–352 (1976)CrossRefGoogle Scholar
  17. 17.
    N.C. Greenham, X. Peng, A.P. Alivisatos, Charge separation and transport in conjugated-polymer/semiconductor-nanocrystal composites studied by photoluminescence quenching and photoconductivity. Phys. Rev. B 54, 17628–17637 (1996)CrossRefGoogle Scholar
  18. 18.
    D. de Nobel, Phase equilibria and semiconducting properties of cadmium telluride. Philips Res. Repts 14, 361–399 (1959)Google Scholar
  19. 19.
    C.A. Colinge, Jean-Pierre; Colinge, Physics of Semiconductor Devices (Kluwer Academic Publishers, Newyork, 2002)Google Scholar
  20. 20.
    S.M. Sze, K.K. Ng, Physics of Semiconductor Devices, 3rd edn. (Wiley, Hoboken, 2007)Google Scholar
  21. 21.
    J.S. Kim, J.H. Park, J.H. Lee, J. Jo, D.Y. Kim, K. Cho, Control of the electrode work function and active layer morphology via surface modification of indium tin oxide for high efficiency organic photovoltaics. Appl. Phys. Lett. 91, 1–4 (2007)Google Scholar
  22. 22.
    A.M. Al-Enizi, A.A. Elzatahry, A.M. Abdullah, A. Vinu, H. Iwai, S.S. Al-Deyab, High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium. Appl. Surf. Sci. 401, 306–313 (2017)CrossRefGoogle Scholar
  23. 23.
    J. Wang, P. Lv, Y. Mu, D. Ding, L. Liu, A. Runa, F. Feng, S. Feng, W. Fu, H. Yang, A novel cage-like CdTe film with enhanced photoelectrochemical performance. RSC Adv. 6, 43489–43495 (2016)CrossRefGoogle Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Solar Cell Laboratory, Physics Department, Sciences and Arts FacultyUludag UniversityBursaTurkey

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