Atomic force microscopy analysis of alkali textured silicon substrates for solar cell applications

  • Authors

    • Adebayo Fashina Tubman University
    • Kenneth Adama Federal University, Ndufu-Alike Ikwo
    • Lookman Abdullah King Faisal Specialist Hospital and Research Center
    • Chukwuemeka Ani African University of Science and Technology, Abuja
    • Oluwaseun Oyewole Baze University
    • Joseph Asare Baze University
    • Vitalis Anye Nile University of Nigeria
    2018-01-17
    https://doi.org/10.14419/ijpr.v6i1.8795
  • AFM, Surface Texturing, Surface Roughness, Pyramid Formation and C-Si Solar Cell.

  • In this paper, the surface morphology of textured silicon substrates is explored. Prior to the surface morphology analysis, textured silicon substrates were obtained by KOH anisotropic texturing of polished silicon wafers. This was achieved by investigating of the dependence surface texturing on the process parameters; etchant concentration, etching time and temperature. The surface morphology of the textured silicon samples was obtained using atomic force microscopy that was operated in the tapping mode. The resulting atomic force microscopy (AFM) images were analyzed using the Nanoscope and Gwyddion software packages. The AFM analysis revealed more surface details such as the depth, roughness, section, and step height analysis. The analysis was limited to a length scale of a few micrometers, which carefully reveals the number of individualities of the initial stages of pyramid growth. The average roughness was found to be 593nm for an optimally textured silicon wafer. The implications of the study are then discussed for potential light trapping application in silicon solar cells.

  • References

    1. [1] IRENA. Solar PV in Africa: Costs and Markets; IRENA: Masdar City, United Arab Emirates, 2016.

      [2] Saga T. Crystalline and Polycrystalline Silicon PV Technology. NPG Asia mater, 2(3), (2010) 96-102. https://doi.org/10.1038/asiamat.2010.82.

      [3] Li H.H. Refractive index of silicon and germanium and its wavelength and temperature derivatives. J. Phy. Chem. Reference Data, 9(3), (1980) 561-658. https://doi.org/10.1063/1.555624.

      [4] Gee J.; Wenham S. Advanced Processing of Silicon Solar Cells, Tutorial Notebook of the 23rd IEEE Photovoltaic Specialists Conference, Louisville, Ohio, USA 1993.

      [5] Barnett A.M. Thin Film Solar Cell Comparison Methodology, Proceedings of the 14th IEEE Photovoltaic Specialists Conference, San Diego, California,USA 1980, pp. 273-280.

      [6] Campbell P.; Green M.A. Light Trapping Properties of Pyramidally Textured Surfaces. J. Appl. Phys. 62(1), (1987) 243-249. https://doi.org/10.1063/1.339189.

      [7] King D.L.; Buck M.E. Experimental Optimization of an Anisotropic Etching Process for Random Texturization of Silicon Solar Cells, Proceedings of the 22nd IEEE Photovoltaic Specialists Conference, Las Vegas, USA 1991, pp. 303-308.

      [8] Green, M.A.; Emery K.; Hishikawa, Y.; Warta W.; Dunlop E.D. Solar cell efficiency tables (version 46). Progress in Photovoltaics: Research and Applications, 23(7), (2015) 805-812. https://doi.org/10.1002/pip.2637.

      [9] Fashina A.A.; Adama K.K.; Oyewole O.K.; Anye V.C.; Asare J.; Zebaze Kana M.G.; Soboyejo W.O. Surface texture and optical properties of crystalline silicon substrates. J. Renew. Sus. Ener., 7(6), (2015) 063119-1 - 063119-11.

      [10] Wijekoon, K; Weidman T.; Paak, S.; MacWilliams K. Production Ready Novel Texture Etching Process for Fabrication of Single Crystalline Silicon Solar Cells, Proceedings of the 35th IEEE Photovoltaic Specialists Conference, Honolulu, USA 2010, pp. 3635-3641.

      [11] Chung, H.Y., Chen C.H.; Chu, H.S. Analysis of Pyramidal Surface Texturization of Silicon Solar Cells by Molecular Dynamics Simulations. Int. J. Photoener. (2008) 1-6.

      [12] Fashina A.A.; Zebaze Kana M.G.; Soboyejo W.O. Optical reflectance of alkali-textured silicon wafers with pyramidal facets: 2D analytical model. J. Mater. Res., 3(7), (2015) 904 - 913. https://doi.org/10.1557/jmr.2015.70.

      [13] Seidel H.; Csepregi L.; Heuberger A.; Baumgärtel H. Anisotropic Etching of Crystalline Silicon in Alkaline Solution: Orientation Dependence and Behavior of Passivation Layers. J. Electrochem. Soc. 137(11), (1990) 612- 626. https://doi.org/10.1149/1.2086277.

      [14] Kilpinen P.; Haimi E.; Lindroos V.K.The Etch Rate Variations of p+ Silicon Wafers in Aqueous KOH Solutions as a Function of Processing Conditions. In MRS Proceedings 605, (1999) 293. https://doi.org/10.1557/PROC-605-293.

      [15] Shikida M.; Sato K.; Tokoro K.; Uchikawa D. Differences in Anisotropic Etching Properties of KOH and TMAH Solution. Sens. Actuat. A80, (1999) 179-188.

      [16] Sato K.; Shikida M.; Yamashiro T.; Tsunekawa M.; Ito S. Roughening of Single-Crystal Silicon Surface Etched by KOH Water Solutions. Sens. Actuat. A73, (1999) 122-130. https://doi.org/10.1016/S0924-4247(98)00270-2.

      [17] Zubel I.; Kramkowska M. The Effect of Isopropyl Alcohol on Etching Rate and Roughness of (100) Si Surface Etched in KOH and TMAH Solutions. Sens. Actuat. A93, (2001) 138-147. https://doi.org/10.1016/S0924-4247(01)00648-3.

      [18] Kassel L.E. KOH-ETCH Related Defects on Processed Silicon Wafers. In MRS Proceedings 259, (1992) 187. https://doi.org/10.1557/PROC-259-187.

      [19] Seidel H.; Csepregi L.; Heuberger A.; Baumgärtel H. Anisotropic Etching of Crystalline Silicon in Alkaline Solutions II. Influence of dopants. J. Electrochem. Soc. 137(11), (1990) 3626-3632. https://doi.org/10.1149/1.2086278.

      [20] Yang C.; Chen P.; Chiou Y.; Lee R. Effects of Mechanical Agitation and Surfactant Additive on Silicon Anisotropic Etching in Alkaline KOH Solution, Sens. Actuat. A119, (2005) 263-270. https://doi.org/10.1016/j.sna.2004.07.015.

      [21] Fashina A.A.; Adama K.K.; Zebaze M.G.; Soboyejo W.O. Improving the Performance of Light Trapping in Crystalline Silicon Solar Cell through Effective Surface Texturing. Trans Tech Publications, 1132, (2016) 144-159.

      [22] Kosolobov S.S.; Nasimov D.A.; Sheglov D.V.; Rodyakina E.E.; Latyshev A.V. Atomic force microscopy of silicon stepped surface. PHYS. LOW DIMEN. STRUCT, 5(6), (2002) 231-238.

      [23] Sarto F.; Castagna E.; Sansovini M.; Lecci S.; Violante V.; Knies D.L.; Grabowski K.S.; Hubler G.K. Electrode Surface Morphology Characterization by Atomic Force Microscopy. ICCF-14 International Conference on Condensed Matter Nuclear Science. 2008. Washington, DC, USA vol. 2, pp. 437-443.

      [24] Dubey R.S.; Gautam D.K. Synthesis and Characterization of Nanocrystalline Porous Silicon Layer for Solar Cells Applications. J. Optoelect. Biomed. Mater, 1(1), (2009), 8-14.

      [25] Xiao Z.; Xu M.; Ohgi T.; Onishi K.; Fujita D. Removal of Si (111) wafer surface etch pits generated in ammonia-peroxide clean step. Appl. Surf. Sci. 221, (2004) 160–166. https://doi.org/10.1016/S0169-4332(03)00876-6.

      [26] Seeger A. (2004) Surface reconstruction from AFM and SEM images (pp. 6482-6482). University of North Carolina at Chapel Hill.

      [27] Giessibl F.J. Advances in atomic force microscopy. Reviews of modern physics, 75(3), (2003) 949. https://doi.org/10.1103/RevModPhys.75.949.

      [28] Garcıa R.; Perez R. Dynamic atomic force microscopy methods. Surf. sci. rep., 47(6), (2002) 197-301. https://doi.org/10.1016/S0167-5729(02)00077-8.

      [29] Oh J.; Yuan H.C.; Branz H.M. An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures. Nature nanotechnology, 7(11), (2012)743-748. https://doi.org/10.1038/nnano.2012.166.

      [30] Kim K.; Dhungel S.K.; Jung S.; Mangalaraj D.; Yi J. Texturing of large area multi-crystalline silicon wafers through different chemical approaches for solar cell fabrication. Sol. Ener. Mater. Sol. Cells, 92(8), (2008) 960-968. https://doi.org/10.1016/j.solmat.2008.02.036.

      [31] Priolo F.; Gregorkiewicz T.; Galli M.; Krauss T.F. Silicon nanostructures for photonics and photovoltaics. Nature nanotecnology, 9(1), (2014) 19-32.

      [32] Brongersma M.L.; Cui Y.; Fan, S. Light management for photovoltaics using high-index nanostructures. Nature materials, 13(5), (2014) 451-460. https://doi.org/10.1038/nmat3921.

      [33] Beard M.C.; Luther J.M.; Nozik, A.J. The promise and challenge of nanostructured solar cells. Nature nanotechnology, 9(12), (2014) 951-954. https://doi.org/10.1038/nnano.2014.292.

      [34] Cai J.; Qi L.; Recent advances in antireflective surfaces based on nanostructure arrays. Materials Horizons, 2(1), (2015) 37-53. https://doi.org/10.1039/C4MH00140K.

      [35] O’Mara W.C.; Herring R.B.; Hunt L.P. Handbook of Semiconductor Silicon Technology, William Andrew Inc., Norwich, NY, 1990: pp. 349–352.

      [36] Parretta A.; Sarno A.; Tortora P.; Yakubu H.; Maddalena P.; Zhao J.; Wang A. Angle dependent reflectance measurements on photovoltaic materials and solar cells. Opt. Commun. 172(1–6), (1999) 139–151. https://doi.org/10.1016/S0030-4018(99)00561-1.

      [37] Fashina A.A.; On the Effect of Surface Texture and Nanoscale Sur-face Oxides on the Optical and Mechanical Properties of Silicon Single Crystals and MEMS Thin films, PhD Thesis AUST, Abuja, Nigeria. (2015).

      [38] Bakerâ€Finch S.C.; McIntosh K.R. Reflection distributions of textured monocrystalline silicon: Implications for silicon solar cells. Prog. Photovoltaics Res. Appl. 21(5), (2013) 960–971. https://doi.org/10.1002/pip.2186.

      [39] Bakerâ€Finch S.C.; McIntosh K.R. Reflection of normally incident light from silicon solar cells with pyramidal texture. Prog. Photovoltaics Res. Appl. 19(4), (2011) 406–416. https://doi.org/10.1002/pip.1050.

      [40] McIntosh K.R.; Bakerâ€Finch S.C. OPAL 2: Rapid optical simulation of silicon solar cells. In Proceedings of the 38th IEEE Photovoltaic Specialists Conference, Austin, TX, USA, 2012; pp. 265–271. https://doi.org/10.1109/PVSC.2012.6317616.

      [41] Bakerâ€Finch S.C.; McIntosh K.R. A freeware program for precise optical analysis of the front surface of a solar cell. In Proceedings of the 35th IEEE Photovoltaic Specialists Conference, Honolulu, HI, 2010; pp. 2184–2187. https://doi.org/10.1109/PVSC.2010.5616132.

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  • How to Cite

    Fashina, A., Adama, K., Abdullah, L., Ani, C., Oyewole, O., Asare, J., & Anye, V. (2018). Atomic force microscopy analysis of alkali textured silicon substrates for solar cell applications. International Journal of Physical Research, 6(1), 13-17. https://doi.org/10.14419/ijpr.v6i1.8795