Advertisement

Real Time and Mapping Spectroscopic Ellipsometry of Hydrogenated Amorphous and Nanocrystalline Si Solar Cells

  • Zhiquan Huang
  • Lila R. Dahal
  • Sylvain Marsillac
  • Nikolas J. PodrazaEmail author
  • Robert W. Collins
Chapter
Part of the Springer Series in Optical Sciences book series (SSOS, volume 214)

Abstract

Real time spectroscopic ellipsometry (SE) has been applied to characterize the structural evolution and optical properties of the critical p-type doped and intrinsic hydrogenated silicon (Si:H) layers that comprise the nanocrystalline Si:H bottom cell of tandem photovoltaic (PV) devices. The tandem PV devices under study are fabricated in the amorphous/nanocrystalline Si:H (a-Si:H/nc-Si:H) p-i-n superstrate configuration in which the nc-Si:H cell is at the bottom of the device structure due to its narrower bandgap relative to that of the top cell a-Si:H. SE data collected in real time during Si:H solar cell fabrication by plasma enhanced chemical vapor deposition (PECVD) enable identification of Si crystallite development in the bottom cell p and i-layers through the evolution of surface roughness, as well as through variations in the optical properties in the form of the complex dielectric function \( (\varepsilon = \varepsilon_{1} - {\text{i}}\varepsilon_{2} ) \). Analysis of the dielectric function permits quantification of the relative amounts of the a-Si-H and nc-Si-H components that exist during the growth of mixed-phase Si:H layers. Based on these real time SE analysis results, a PECVD growth evolution diagram has been developed for the bottom cell i-layer of the tandem PV cell in order to guide fabrication in this device configuration. Correlations between the p and i-layer structures and device performance are evident and can be understood on the basis of the growth evolution diagram. A second growth evolution diagram has been developed to characterize PECVD of n-type Si-H thin films for use as the n-layer component of p-i-n a-Si:H top cells in the same superstrate configuration. This growth evolution diagram has been established to provide guidance for PECVD of the n-layers over the 15 cm × 15 cm areas of glass/TCO/p/i superstrates, where TCO represents the transparent conducting oxide layer serving as the topmost contact. The goal of this study is to correlate the structural characteristics provided by the diagram with the performance parameters of single-junction a-Si:H solar cells that can serve as the top cell of the tandem device. A 16 × 16 array of p-i-n dot cells has been fabricated over the 15 cm × 15 cm area of the TCO coated glass superstrate, and this same area has been studied by mapping SE. Analysis of the SE data collected over the full area provides maps of the p-layer effective thickness, i-layer thickness and bandgap, and n-layer thickness and nanocrystalline volume fraction for spatial correlation with the performance parameters from current density-voltage (J-V) measurements of the 16 × 16 array of dot cells. The goal of the correlations that exploit mapping SE is to identify and understand the relationships between the variations in the basic materials properties and in the thin film solar cell performance over large areas. The results also enable analysis of the impacts of spatial non-uniformities on PV module performance.

References

  1. 1.
    E.A. Schiff, S. Hegedus, X. Deng, in Handbook of Photovoltaic Science and Engineering, 2nd edn., ed. by A. Luque, S. Hegedus (Wiley, New York, NY, 2011), Chapter 12, p. 487Google Scholar
  2. 2.
    A. Shah (ed.), Thin Film Silicon Solar Cells (CRC, Boca Raton, FL, 2010)Google Scholar
  3. 3.
    J. Meier, S. Dubail, R. Platz, P. Torres, U. Kroll, J.A. Anna Selvan, N. Pellaton Vaucher, C. Hof, D. Fischer, H. Keppner, R. Fluckiger, A. Shah, V. Shklover, K.D. Ufert, Solar Energy Mater. Solar Cells 78, 35 (1997)CrossRefGoogle Scholar
  4. 4.
    A. Shah, J. Meier, E. Vallat-Sauvain, N. Wyrsch, U. Kroll, C. Droz, U. Graf, Solar Energy Mater. Solar Cells 78, 469 (2003)CrossRefGoogle Scholar
  5. 5.
    X. Cao, J.A. Stoke, J. Li, N.J. Podraza, W. Du, X. Yang, D. Attygalle, X. Liao, R.W. Collins, X. Deng, J. Non-Cryst. Solids 354, 2397 (2008)ADSCrossRefGoogle Scholar
  6. 6.
    B. Yan, G. Yue, L. Sivec, J. Yang, S. Guha, C.-S. Jiang, Appl. Phys. Lett. 99, 113512 (2011)ADSCrossRefGoogle Scholar
  7. 7.
    T. Matsui, H. Sai, K. Saito, M. Kondo, Prog. Photovolt.: Res. Appl. 21, 1363 (2013)CrossRefGoogle Scholar
  8. 8.
    H. Sai, T. Matsui, K. Matsubara, M. Kondo, I. Yoshida, IEEE J. Photovolt. 4, 1349 (2014)CrossRefGoogle Scholar
  9. 9.
    M.A. Green, K. Emery, Y. Hishikawa, W. Warta, E.D. Dunlop, D.H. Levi, A.W.Y. Ho-Baillie, Prog. Photovolt.: Res. Appl. 25, 3 (2017)Google Scholar
  10. 10.
    O. Vetterl, F. Finger, R. Carius, P. Hapke, L. Houben, O. Kluth, A. Lambertz, A. Muck, B. Rech, H. Wagner, Solar Energy Mater. Solar Cells 62, 97 (2000)CrossRefGoogle Scholar
  11. 11.
    R.W. Collins, A.S. Ferlauto, G.M. Ferreira, C. Chen, J. Koh, R.J. Koval, Y. Lee, J.M. Pearce, C.R. Wronski, Solar Energy Mater. Solar Cells 78, 143 (2003)CrossRefGoogle Scholar
  12. 12.
    L.R. Dahal, J. Li, J.A. Stoke, Z. Huang, A. Shan, A.S. Ferlauto, C.R. Wronski, R.W. Collins, N.J. Podraza, Solar Energy Mater. Solar Cells 129, 32 (2014)CrossRefGoogle Scholar
  13. 13.
    H. Fujiwara, Spectroscopic Ellipsometry: Principles and Applications (Wiley, Chichester, UK, 2007)CrossRefGoogle Scholar
  14. 14.
    Z. Huang, L.R. Dahal, M.M. Junda, P. Aryal, S. Marsillac, R.W. Collins, N.J. Podraza, IEEE J. Photovolt. 5, 1516 (2015)CrossRefGoogle Scholar
  15. 15.
    Z. Huang, in Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration. Ph.D. Dissertation (University of Toledo, Toledo, OH, 2016)Google Scholar
  16. 16.
    Z. Huang, L.R. Dahal, C. Salupo, A.S. Ferlauto, N.J. Podraza, R.W. Collins, in Conference Record of the 39th IEEE Photovoltaics Specialists Conference, Tampa, FL, 16–21 June 2013 (IEEE, New York, 2013), p. 1788Google Scholar
  17. 17.
    J. Koh, Y.W. Lu, S. Kim, J.S. Burnham, C.R. Wronski, R.W. Collins, Appl. Phys. Lett. 67, 2669 (1995)ADSCrossRefGoogle Scholar
  18. 18.
    I. An, Y.M. Li, H.V. Nguyen, C.R. Wronski, R.W. Collins, Appl. Phys. Lett. 59, 2543 (1991)ADSCrossRefGoogle Scholar
  19. 19.
    B. Johs, J.S. Hale, Phys. Stat. Solidi (a) 205, 715 (2008)ADSCrossRefGoogle Scholar
  20. 20.
    R.W. Collins, A.S. Ferlauto, in Handbook of Ellipsometry, ed. by H.G. Tompkins, E.A. Irene (William Andrew, Norwich, NY, 2005), Chapter 2, p. 93Google Scholar
  21. 21.
    M.M. Junda, A. Shan, P. Koirala, R.W. Collins, N.J. Podraza, IEEE J. Photovolt. 5, 307 (2015)CrossRefGoogle Scholar
  22. 22.
    A.S. Ferlauto, G.M. Ferreira, R.J. Koval, J.M. Pearce, C.R. Wronski, R.W. Collins, M.M. Al-Jassim, K.M. Jones, Thin Solid Films 455–456, 665 (2004)CrossRefGoogle Scholar
  23. 23.
    J.A. Stoke, L.R. Dahal, J. Li, N.J. Podraza, X. Cao, X. Deng, R.W. Collins, in Conference Record of the 33rd IEEE Photovoltaics Specialist Conference, San Diego, CA, 11–16 May 2008 (IEEE, New York, 2008), Paper 413Google Scholar
  24. 24.
    D.E. Aspnes, J. Opt. Soc. Am. A 10, 974 (1993)ADSCrossRefGoogle Scholar
  25. 25.
    S. Kim, R.W. Collins, Appl. Phys. Lett. 67, 3010 (1995)ADSCrossRefGoogle Scholar
  26. 26.
    A.S. Ferlauto, G.M. Ferreira, J.M. Pearce, C.R. Wronski, R.W. Collins, X. Deng, G. Ganguly, J. Appl. Phys. 92, 2424 (2002)ADSCrossRefGoogle Scholar
  27. 27.
    T. Yuguchi, Y. Kanie, N. Matsuki, H. Fujiwara, J. Appl. Phys. 111, 083509 (2012)ADSCrossRefGoogle Scholar
  28. 28.
    K. von Rottkay, M. Rubin, Materials Research Society Symposium Proceedings: Thin Films for Photovoltaic and Related Devices, vol. 426 (MRS, Warrendale, PA, 1996), p. 449Google Scholar
  29. 29.
    J. Chen, J. Li, D. Sainju, K.D. Wells, N.J. Podraza, R.W. Collins, in Conference Record of the IEEE 4th World Conference on Photovoltaic Energy Conversion 2006, Waikoloa, HI, 7–12 May 2006 (IEEE, New York, NY, 2006), p. 475Google Scholar
  30. 30.
    N.J. Podraza, C.R. Wronski, M.W. Horn, R.W. Collins, Materials Research Society Symposium Proceedings: Amorphous and Polycrystalline Thin-Film Silicon Science and Technology—2006, vol. 910 (MRS, Warrendale, PA, 2006), p. 259Google Scholar
  31. 31.
    H.V. Nguyen, R.W. Collins, Phys. Rev. B 47, 1911 (1993)ADSCrossRefGoogle Scholar
  32. 32.
    P. Etchegoin, J. Kircher, M. Cardona, Phys. Rev. B 47, 10292 (1993)ADSCrossRefGoogle Scholar
  33. 33.
    P. Lautenschlager, M. Garriga, L. Viña, M. Cardona, Phys. Rev. B 36, 4821 (1987)ADSCrossRefGoogle Scholar
  34. 34.
    Z. Huang, J. Chen, M.N. Sestak, D. Attygalle, L.R. Dahal, M.R. Mapes, D.A. Strickler, K.R. Kormanyos, C. Salupo, R.W. Collins, in Conference Record of the 35th IEEE Photovoltaic Specialists Conference, Honolulu, HI, 20–25 June 2010 (IEEE, New York, NY, 2010), p. 1678Google Scholar
  35. 35.
    J. Chen, P. Koirala, C. Salupo, R.W. Collins, S. Marsillac, K.R. Kormanyos, B.D. Johs, J.S. Hale, G.L. Pfeiffer, in Conference Record of the 38th IEEE Photovoltaic Specialists Conference, Austin, TX, 3–8 June 2012 (IEEE, New York, NY, 2012), p. 377Google Scholar
  36. 36.
    R.W. Collins, B.Y. Yang, J. Vac. Sci. Technol. B 7, 1155 (1989)CrossRefGoogle Scholar
  37. 37.
    Y.A. Kryukov, N.J. Podraza, R.W. Collins, J. Amar, Phys. Rev. B 80, 085403 (2009)ADSCrossRefGoogle Scholar
  38. 38.
    C.W. Teplin, C.-S. Jiang, P. Stradins, H.M. Branz, Appl. Phys. Lett. 92, 093114 (2008)ADSCrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Zhiquan Huang
    • 1
  • Lila R. Dahal
    • 1
  • Sylvain Marsillac
    • 2
  • Nikolas J. Podraza
    • 1
    Email author
  • Robert W. Collins
    • 1
  1. 1.Department of Physics & Astronomy and Center for Photovoltaics Innovation & CommercializationUniversity of ToledoToledoUSA
  2. 2.Virginia Institute of Photovoltaics, Old Dominion UniversityNorfolkUSA

Personalised recommendations