Light Trapping in Coaxial Nanowires of c-Si Cores and a-Si Shells

  • Jeong Il Oh
  • Wenfu Liu
  • Weiqiang Xie
  • Wenzhong ShenEmail author
Part of the Springer Series in Materials Science book series (SSMATERIALS, volume 187)


Light absorption is investigated in coaxial nanowires (NWs) of crystalline silicon (c-Si) cores and amorphous silicon (a-Si) shells, including both cases of single coaxial NWs and coaxial NW arrays, for an incident light spectrum of 1.0–4.0 eV covering the major solar band for photovoltaic cells. Based on the Lorenz-Mie light scattering theory for the single coaxial NWs and the rigorous coupled-wave analysis method for the coaxial NW arrays, it is found that the incident light is effectively trapped in the coaxial NWs through absorption resonances so that the light absorption of the coaxial NWs can be significantly enhanced compared to that of c-Si NWs. In the coaxial NWs, the absorption resonances occur due to their subwavelength dimensions, as in the c-Si NWs, whereas the absorption enhancement originates from the a-Si shells. By tuning their structural parameters, the light absorption in the coaxial NWs can be readily optimized for photovoltaic applications. At the optimal absorption conditions, the photocurrent in the coaxial NWs can be enhanced up to 560 % (single case) and 14 % (array case) compared to that in the c-Si NWs. The underlying physics of the light absorption in the coaxial NWs is discussed in terms of the excitation of leaky-mode resonances. The practical use of the coaxial NWs for photovoltaic cells is also addressed.


Light trapping  Coaxial nanowires Single coaxial nanowires Coaxial nanowire arrays Crystalline silicon cores Amorphous silicon shells Silicon nanowires Planar coaxial nanowire arrays Leaky-mode resonances RCWA Lorenz-Mie Maxwell’s equations Photovoltaic cells Solar cells Light absorption Light absorption efficiency Omnidirectional light absorption Photocurrent density Short-circuit current density Open-circuit voltage Photocurrent enhancement factor TE-polarization TM-polarization Absorption cross section Geometrical cross section Grating Refractive index Relative permittivity Diffraction order Subwavelength Space-harmonic fields Fabry-Pérot resonances Light interference Nanoelectronic 



This work was supported by the National Major Basic Research Project of 2012CB934302 and the Natural Science Foundation of China under contracts 11074169, 11174202, and 61234005.


  1. 1.
    Nelson, J.: The Physics of Solar Cells. Imperial College Press, London (2003)Google Scholar
  2. 2.
    Dale, B., Rudenberg, H.G.: High efficiency silicon solar cells. In: Proceedings of the 14th Annual Power Sources Conference, p 22 (1960)Google Scholar
  3. 3.
    Pillai, S., Catchpole, K.R., Trupke, T., Green, M.A.: Surface plasmon enhanced silicon solar cells. J. Appl. Phys. 101, 093105 (2007)CrossRefGoogle Scholar
  4. 4.
    Beck, F.J., Polman, A., Catchpole, K.R.: Tunable light trapping for solar cells using localized surface plasmons. J. Appl. Phys. 105, 114310 (2009)CrossRefGoogle Scholar
  5. 5.
    Ferry, V.E., Verschuuren, M.A., Li, H.B.B.T., Schropp, R.E.I., Atwater, H.A., Polman, A.: Improved red-response in thin film a-Si:H solar cells with soft-imprinted plasmonic back reflectors. Appl. Phys. Lett. 95, 183503 (2009)CrossRefGoogle Scholar
  6. 6.
    Atwater, H.A., Polman, A.: Plasmonics for improved photovoltaic devices. Nat. Mater. 9, 205–213 (2010)Google Scholar
  7. 7.
    Ferry, V.E., Verschuuren, M.A., Li, H.B.B.T., Verhagen, E., Walters, R.J., Schropp, R.E.I., Atwater, H.A., Polman, A.: Light trapping in ultrathin plasmonic solar cells. Opt. Express 18, A237–A245 (2010)CrossRefGoogle Scholar
  8. 8.
    Chen, X., Jia, B.H., Saha, J.K., Cai, B.Y., Stokes, N., Qiao, Q., Wang, Y.Q., Shi, Z.R., Gu, M.: Broadband enhancement in thin-film amorphous silicon solar cells enabled by nucleated silver nanoparticles. Nano Lett. 12, 2187–2192 (2012)CrossRefGoogle Scholar
  9. 9.
    Nunomura, S., Minowa, A., Sai, H., Kondo, M.: Mie scattering enhanced near-infrared light response of thin-film silicon solar cells. Appl. Phys. Lett. 97, 063507 (2010)CrossRefGoogle Scholar
  10. 10.
    Muskens, O.L., Rivas, J.G., Algra, R.E., Bakkers, E.P.A.M., Lagendijk, A.: Design of light scattering in nanowire materials for photovoltaic applications. Nano Lett. 8, 2638–2642 (2008)CrossRefGoogle Scholar
  11. 11.
    Cao, L.Y., White, J.S., Park, J.S., Schuller, J.A., Clemens, B.M., Brongersma, M.L.: Engineering light absorption in semiconductor nanowire devices. Nat. Mater. 8, 643–647 (2009)CrossRefGoogle Scholar
  12. 12.
    Pei, Z.W., Chang, S.T., Liu, C.W., Chen, Y.C.: Numerical simulation on the photovoltaic behavior of an amorphous-silicon nanowire-array solar cell. IEEE. Electron Device Lett. 30, 1305–1307 (2009)Google Scholar
  13. 13.
    Liu, W.F., Oh, J.I., Shen, W.Z.: Light trapping in single coaxial nanowires for photovoltaic applications. IEEE. Electron Device Lett. 32, 45–47 (2010)CrossRefGoogle Scholar
  14. 14.
    Diedenhofen, S.L., Janssen, O.T.A., Grzela, G., Bakkers, E.P.A.M., Rivas, J.G.: Strong geometrical dependence of the absorption of light in arrays of semiconductor nanowires. ACS Nano. 5, 2316–2323 (2011)CrossRefGoogle Scholar
  15. 15.
    Tian, B.Z., Zheng, X.L., Kempa, T.J., Fang, Y., Yu, N.F., Yu, G.H., Huang, J.L., Lieber, C.M.: Coaxial silicon nanowires as solar cells and nanoelectronic power sources. Nature 449, 885–890 (2007)CrossRefGoogle Scholar
  16. 16.
    Kempa, T.J., Tian, B.Z., Kim, D.R., Hu, J.S., Zheng, X.L., Lieber, C.M.: Single and tandem axial p-i-n nanowire photovoltaic devices. Nano Lett. 8, 3456–3460 (2008)CrossRefGoogle Scholar
  17. 17.
    Tian, B.Z., Kempa, T.J., Lieber, C.M.: Single nanowire photovoltaics. Chem. Soc. Rev. 38, 16–24 (2009)CrossRefGoogle Scholar
  18. 18.
    Kim, S.K., Day, R.W., Cahoon, J.F., Kempa, T.J., Song, K.D., Park, H.G., Lieber, C.M.: Tuning light absorption in core/shell silicon nanowire photovoltaic devices through morphological design. Nano Lett. 12, 4971–4976 (2012)Google Scholar
  19. 19.
    Hu, L., Chen, G.: Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications. Nano Lett. 7, 3249–3252 (2007)CrossRefGoogle Scholar
  20. 20.
    Lin, C.X., Povinelli, M.L.: Optical absorption enhancement in silicon nanowire arrays with a large lattice constant for photovoltaic applications. Opt. Express 17, 19371–19381 (2009)CrossRefGoogle Scholar
  21. 21.
    Li, J.S., Yu, H.Y., Wong, S.M., Li, X.C., Zhang, G., Lo, P.G.Q., Kwong, D.L.: Design guidelines of periodic Si nanowire arrays for solar cell application. Appl. Phys. Lett. 95, 243113 (2009)CrossRefGoogle Scholar
  22. 22.
    Tsakalakos, L., Balch, J., Fronheiser, J., Korevaar, B.A., Sulima, O., Rand, J.: Silicon nanowire solar cells. Appl. Phys. Lett. 91, 233117 (2007)CrossRefGoogle Scholar
  23. 23.
    Stelzner, T., Pietsch, M., Andrä, G., Falk, F., Ose, E., Christiansen, S.: Silicon nanowire-based solar cells. Nanotechnology 19, 295203 (2008)CrossRefGoogle Scholar
  24. 24.
    Fang, H., Li, X.D., Song, S., Xu, Y., Zhu, J.: Fabrication of slantingly-aligned silicon nanowire arrays for solar cell applications. Nanotechnology 19, 255703 (2008)CrossRefGoogle Scholar
  25. 25.
    Garnett, E.C., Yang, P.D.: Silicon nanowire radial p-n junction solar cells. J. Am. Chem. Soc. 130, 9224–9225 (2008)CrossRefGoogle Scholar
  26. 26.
    Gunawan, O., Guha, S.: Characteristics of vapor-liquid-solid grown silicon nanowire solar cells. Sol. Energy Mater. Sol. Cells 93, 1388–1393 (2009)CrossRefGoogle Scholar
  27. 27.
    Bao, H., Ruan, X.L.: Optical absorption enhancement in disordered vertical silicon nanowire arrays for photovoltaic applications. Opt. Lett. 35, 3378–3380 (2010)CrossRefGoogle Scholar
  28. 28.
    Garnett, E., Yang, P.D.: Light trapping in silicon nanowiresolar cells. Nano Lett. 10, 1082–1087 (2010)CrossRefGoogle Scholar
  29. 29.
    Adachi, M.M., Anantram, M.P., Karim, K.S.: Optical properties of crystalline-amorphous core-shell silicon nanowires. Nano Lett. 10, 4093–4098 (2010)CrossRefGoogle Scholar
  30. 30.
    Chen, C., Jia, R., Yue, H.H., Li, H.F., Liu, X.Y., Wu, D.Q., Ding, W.C., Ye, T.C., Kasai, S., Tamotsu, H., Chu, J.H., Wang, S.L.: Silicon nanowire-array-textured solar cells for photovoltaic application. J. Appl. Phys. 108, 094318 (2010)CrossRefGoogle Scholar
  31. 31.
    Xie, W.Q., Oh, J.I., Shen, W.Z.: Realization of effective light trapping and omnidirectional antireflection in smooth surface silicon nanowirearrays. Nanotechnology 22, 065704 (2011)CrossRefGoogle Scholar
  32. 32.
    Cao, L.Y., Fan, P.Y., Vasudev, A.P., White, J.S., Yu, Z.F., Cai, W.S., Schuller, J.A., Fan, S.H., Brongersma, M.L.: Semiconductor nanowireoptical antenna solar absorbers. Nano Lett. 10, 439–445 (2010)CrossRefGoogle Scholar
  33. 33.
    Cao, L.Y., Fan, P.Y., Brongersma, M.L.: Optical coupling of deep-subwavelength semiconductor nanowires. Nano Lett. 11, 1463–1468 (2011)CrossRefGoogle Scholar
  34. 34.
    Wang, B., Leu, P.W.: Tunable and selective resonant absorption in vertical nanowires. Opt. Lett. 37, 3756–3758 (2012)CrossRefGoogle Scholar
  35. 35.
    Kelzenberg, M.D., Boettcher, S.W., Petykiewicz, J.A., Turner-Evans, D.B., Putnam, M.C., Warren, E.L., Spurgeon, J.M., Briggs, R.M., Lewis, N.S., Atwater, H.A.: Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications. Nat. Mater. 9, 239–244 (2010)CrossRefGoogle Scholar
  36. 36.
    Yablonovitch, E.: Statistical ray optics. J. Opt. Soc. Am. 72, 899–907 (1982)CrossRefGoogle Scholar
  37. 37.
    Tiedje, T., Yablonovitch, E., Cody, G.D., Brooks, B.G.: Limiting efficiency of silicon solar-cells. IEEE Trans. Electron Devices 31, 711–716 (1984)CrossRefGoogle Scholar
  38. 38.
    Kosten, E.D., Warren, E.L., Atwater, H.A.: Ray optical light trapping in silicon microwires: exceeding the 2 n\(^{2}\) intensity limit. Opt. Express 19, 3316–3331 (2011)CrossRefGoogle Scholar
  39. 39.
    Palik, E.D.: Handbook of optical constants of solids. Academic Press, London (1985)Google Scholar
  40. 40.
    Shah, A.V., Schade, H., Vanecek, M., Meier, J., Vallat-Sauvain, E., Wyrsch, N., Kroll, U., Droz, C., Bailat, J.: Thin-film silicon solar cell technology. Prog. Photovolt. 12, 113–142 (2004)CrossRefGoogle Scholar
  41. 41.
    Dong, Y.J., Yu, G.H., McAlpine, M.C., Lu, W., Lieber, C.M.: Si/a-Si core/shell nanowires as nonvolatile crossbar switches. Nano Lett. 8, 386–391 (2008)CrossRefGoogle Scholar
  42. 42.
    Taguchi, M., Kawamoto, K., Tsuge, S., Baba, T., Sakata, H., Morizane, M., Uchihashi, K., Nakamura, N., Kiyama, S., Oota, O.: HIT\(^{TM}\) cells-high-efficiency crystalline Si cells with novel structure. Prog. Photovolt. 8, 503–513 (2000)CrossRefGoogle Scholar
  43. 43.
    Bohren, C.F., Huffman, D.R.: Absorption and scattering of light by small particles. Wiley, New York (1998)Google Scholar
  44. 44.
    Moharam, M.G., Gaylord, T.K.: Rigorous coupled-wave analysis of planar-grating diffraction. J. Opt. Soc. Am. 71, 811–818 (1981)CrossRefGoogle Scholar
  45. 45.
    Moharam, M.G., Grann, E.B., Pommet, D.A., Gaylord, T.K.: Formulation for stable and efficient implementation of the rigorous coupled-wave analysis of binary gratings. J. Opt. Soc. Am. A 12, 1068–1076 (1995)CrossRefGoogle Scholar
  46. 46.
    Moharam, M.G., Pommet, D.A., Grann, E.B., Gaylord, T.K.: Stable implementation of the rigorous coupled-wave analysis for surface-relief gratings: enhanced transmittance matrix approach. J. Opt. Soc. Am. A 12, 1077–1086 (1995)CrossRefGoogle Scholar
  47. 47.
    Brönstrup, G., Jahr, N., Leiterer, C., Csáki, A., Fritzsche, W., Christiansen, S.: Optical properties of individual silicon nanowires for photonic devices. ACS Nano 4, 7113–7122 (2010)CrossRefGoogle Scholar
  48. 48.
    Zhu, J., Yu, Z.F., Burkhard, G.F., Hsu, C.M., Connor, S.T., Xu, Y.Q., Wang, Q., McGehee, M., Fan, S.H., Cui, Y.: Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays. Nano Lett. 9, 279–282 (2009)CrossRefGoogle Scholar
  49. 49.
    Lee, Y.J., Ruby, D.S., Peters, D.W., McKenzie, B.B., Hsu, J.W.P.: ZnO nanostructures as efficient antireflection layers in solar cells. Nano Lett. 8, 1501–1505 (2008)CrossRefGoogle Scholar
  50. 50.
    Chiu, C.H., Yu, P.C., Kuo, H.C., Chen, C.C., Lu, T.C., Wang, S.C., Hsu, S.H., Cheng, Y.J., Chang, Y.C.: Broadband and omnidirectional antireflection employing disordered GaN nanopillars. Opt. Express 16, 8748–8754 (2008)CrossRefGoogle Scholar
  51. 51.
    Khoury, C.G., Norton, S.J., Vo-Dinh, T.: Investigating the plasmonics of a dipole-excited silver nanoshell: Mie theory versus finite element method. Nanotechnology 21, 315203 (2010)CrossRefGoogle Scholar
  52. 52.
    Air Mass 1.5 Spectra. American society for testing and materials ( (2012)
  53. 53.
    Liu, W.F., Oh, J.I., Shen, W.Z.: Light absorption mechanism in single c-Si (core)/a-Si (shell) coaxial nanowires. Nanotechnology 22, 125705 (2011)CrossRefGoogle Scholar
  54. 54.
    Xie, W.Q., Liu, W.F., Oh, J.I., Shen, W.Z.: Optical absorption in c-Si/a-Si:H core/shell nanowire arrays for photovoltaic applications. Appl. Phys. Lett. 99, 033107 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Jeong Il Oh
    • 1
  • Wenfu Liu
    • 1
  • Weiqiang Xie
    • 1
  • Wenzhong Shen
    • 1
    Email author
  1. 1.Laboratory of Condensed Matter Spectroscopy and Opto-Electronic Physics, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Institute of Solar EnergyShanghai Jiao Tong UniversityShanghaiChina

Personalised recommendations