Design and analysis of an ultra-thin crystalline silicon heterostructure solar cell featuring SiGe absorber layer

Design and analysis of an ultra-thin crystalline silicon heterostructure solar cell featuring SiGe absorber layer

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Here, the authors studied a silicon–germanium (Si1−x Ge x ) absorber layer for the design and simulation of an ultra-thin crystalline silicon solar cell using Silvaco technology computer-aided design. Seeking ways to design and fabricate solar cells using 100 μm thicker silicon substrates is the subject of intense research efforts among the photovoltaic (PV) community. The aim is to further reduce the substrate thickness to 20 μm without compromising the efficiency of the solar cell. A thin layer of SiGe film with the Ge composition of 15% has been introduced in this work that assists in absorbing the longer wavelength of the sunlight spectrum. The effects of the doping concentration and absorber layer thickness on the conversion efficiency have been examined. The simulated results exhibited significant enhancement in the sunlight absorption as compared to the reference structure based on crystalline silicon. The highest efficiency of 16.8% with an overall solar cell thickness of ∼26 μm has been observed. The proposed heterostructure solar cell design will support the industrial development of an efficient, low-cost, shorter energy payback time, and light-weight PV technology for its widespread implementation.


    1. 1)
      • 1. Sawyer, J.: ‘Man-made carbon dioxide and the “greenhouse” effect’, Nature, 1972, 239, pp. 2326.
    2. 2)
      • 2. Millar, R., Fuglestvedt, J., Friedlingstein, P., et al: ‘Emission budgets and pathways consistent with limiting warming to 1.5°C’, Nat. Geosci., 2017, 10, pp. 741747.
    3. 3)
      • 3. Shakun, J.D., Clark, P., Feng, H., et al: ‘Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation’, Nature, 2012, 484, pp. 4954.
    4. 4)
      • 4. Ricke, K., Caldeira, K.: ‘Maximum warming occurs about one decade after a carbon dioxide emission’, Environ. Res. Lett., 2014, 9, (12), p. 124002.
    5. 5)
      • 5. Report Fraunhofer Institute for Solar Energy Systems (ISE): ‘Photovoltaics report’, Freiburg Germany, 2017, p. 4. Available at:, retrieved 24 November 2017.
    6. 6)
      • 6. Report SolarPower Europe (SPE): ‘Global market outlook 2017–2021’, Brussels, Belgium, 2017, p. 7. Available at:, retrieved 24 November 2017.
    7. 7)
      • 7. Report Solar Power Europe (SPE): ‘Global market outlook for solar power 2015–2019’, Brussels, Belgium, 2015. Available at:, retrieved 10 May 2016.
    8. 8)
      • 8. James, A.: ‘Global PV demand outlook 2015–2020: exploring risk in downstream solar markets solar market research’, 2015. Available at:, retrieved 10 May 2016.
    9. 9)
      • 9. Yoshikawa, K., Kawasaki, H., Yoshida, W., et al: ‘Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%’, Nat. Energy, 2017, 2, p. 17032.
    10. 10)
      • 10. Green, M., Hishikawa, Y., Warta, W., et al: ‘Solar cell efficiency tables (version 50)’, Prog. Photovolt. Res. Appl., 2017, 25, (7), pp. 668676.
    11. 11)
      • 11. Glunz, S., Preu, R., Biro, D.: ‘Crystalline silicon solar cells: state-of-the-art and future developments’, in Sayigh, A. (Ed.): ‘Comprehensive renewable energy’ (Elsevier, 2012, 1), pp. 353387.
    12. 12)
      • 12. Zhang, Y., Stokes, N., Jia, B., et al: ‘Towards ultra-thin plasmonic silicon wafer solar cells with minimized efficiency loss’, Sci. Rep., 2014, 4, p. 4939.
    13. 13)
      • 13. Liu, Z., Yamanaka, M., Takato, H., et al: ‘MBE growth of crystalline SiGe thin films for solar cell applications with precisely controlled heterojunction’. Proc. 37th IEEE Photovoltaic Spec. Conf., Seattle, WA, 2011, pp. 256261.
    14. 14)
      • 14. Maydell, K., Grunewald, K., Kellermann, M., et al: ‘Microcrystalline SiGe absorber layers in thin-film silicon solar cells’, Energy Proc., 2014, 44, pp. 209215.
    15. 15)
      • 15. Wang, Y., Lu, X., Huang, S. R., et al: ‘Heteroepitaxial growth of SiGe on Si by LPE for high efficiency solar cells’. Proc. 34th IEEE Photovoltaic Spec. Conf., Philadelphia, PA, 2009, pp. 16961698.
    16. 16)
      • 16. Diaz, M., Wang, L., Li, D., et al: ‘Tandem GaAsP/SiGe on Si solar cells’, Sol. Energy Mater. Sol. C, 2015, 143, pp. 113119.
    17. 17)
      • 17. Bourzac, K.: ‘Flexible silicon solar cells, thin but efficient solar cells use one-tenth the silicon of conventional cells’, MIT Technology Review: Sustainable Energy, 2008. Available at, retrieved 24 November 2017.
    18. 18)
      • 18. Spitzer, M., Shewchun, J., Vera, E., et al: ‘Ultra high efficiency thin silicon pn junction solar cells using reflecting surfaces’. Proc. 14th Photovoltaic Spec. Conf., 1980, pp. 375380.
    19. 19)
      • 19. Chu, T., Chu, S. S., Stokes, E.: ‘Large grain silicon films on metallurgical silicon substrates for photovoltaic applications’, Sol. Energy Mater. Sol. C, 1980, 2, pp. 265275.
    20. 20)
      • 20. Wang, L., Lochtefeld, A., Han, J., et al: ‘Development of a 16.8% efficient 18-μm silicon solar cell on steel’, IEEE J. Photovoltaics, 2014, 4, (6), pp. 13971404.
    21. 21)
      • 21. Skibitzki, O., Paszuk, A., Hatami, F., et al: ‘Lattice-engineered Si1-xGex-buffer on Si(001) for GaP integration’, J. Appl. Phys., 2014, 115, p. 103501.
    22. 22)
      • 22. Tayanagi, M., Usami, N., Pan, W., et al: ‘Improvement in the conversion efficiency of single-junction SiGe solar cells by intentional introduction of the compositional distribution’, J. Appl. Phys., 2007, 101, (5), p. 54504.
    23. 23)
      • 23. Han, S., Chen, G.: ‘Optical absorption enhancement in silicon nanohole arrays for solar photovoltaics’, Nano Lett.., 2010, 10, (3), pp. 10121015.
    24. 24)
      • 24. Eisele, C., Berger, M., Nerding, M., et al: ‘Laser-crystallized microcrystalline SiGe alloys for thin film solar cells’, Thin Solid Films, 2003, 427, (1–2), pp. 176180.
    25. 25)
      • 25. Said, K., Poortmans, J., Caymax, M., et al: ‘Design, fabrication, and analysis of crystalline Si-SiGe heterostructure thin-film solar cells’, IEEE Trans. Elect. Dev., 1999, 46, (10), pp. 21032110.
    26. 26)
      • 26. Wang, C., Wuu, D., Lein, S., et al: ‘Characterization of nanocrystalline SiGe thin film solar cell with double graded-dead absorption layer’, Int. J. Photoenergy, 2012, 2012, Article ID 890284, DOI: 10.1155/2012/890284.
    27. 27)
      • 27. Zhang, L., Lan, J., Yang, J., et al: ‘Study on the physical properties of indium tin oxide thin films deposited by microwave-assisted spray pyrolysis’, J. Alloys Compd., 2017, 728, pp. 13381345.
    28. 28)
      • 28. Du, G., Chen, B., Chen, N., et al: ‘Efficient boron doping in the back surface field of crystalline silicon solar cells via alloyed-aluminum–boron paste’, IEEE Electron Device Lett., 2012, 33, (4), pp. 573575.
    29. 29)
      • 29. Mehmood, H., Nasser, H., Tauqeer, T., et al: ‘Numerical analysis of silicon heterojunction solar cell based on molybdenum oxide as a back surface field (BSF)’. Proc. 33rd European Photovoltaic Solar Energy Conf. and Exhibition (EU PVSEC), Amsterdam, Holland, 2017, pp. 932936. DOI: 10.4229/EUPVSEC20172017-2CV.2.66.
    30. 30)
      • 30. Mehmood, H., Nasser, H., Ozkol, E., et al: ‘Physical device simulation of partial dopant-free asymmetric silicon heterostructure solar cell (P-DASH) based on hole-selective molybdenum oxide (MoOx) with crystalline silicon (cSi)’. IEEE Int. Conf. Eng. Technology (ICET2017), Antalya, Turkey, August 2017, pp. 16, in press.
    31. 31)
      • 31. Penn, C., Schäffler, F., Bauer, G.: ‘Application of numerical exciton-wave-function calculations to the question of band alignment in Si/Si1 − xGex quantum wells’, Phys. Rev. B, 1999, 59, p. 13314.
    32. 32)
      • 32. Mehmood, H., Nasser, H., Tauqeer, T., et al: ‘Simulation of an efficient silicon heterostructure solar cell concept featuring molybdenum oxide carrier-selective contact’, Int. J. Energy Res., 2017, in press, DOI: 10.1002/er.3947.
    33. 33)
      • 33. Vasileska, D., Goodnick, S.: ‘Computational electronics’ (Morgan & Claypool Publishers, USA, 2006, 1st edn.), p. 197.
    34. 34)
      • 34. Kumar, M.: ‘Computer aided design of micro- and nanoelectronic devices’ (World Scientific Publishing Co. Ltd., Singapore, 2016), pp. 175.
    35. 35)
      • 35. Green, M.: ‘Self-consistent optical parameters of intrinsic silicon at 300 K including temperature coefficients’, Sol. Energy Mater. Sol. C., 2008, 92, (11), pp. 13051310.
    36. 36)
      • 36. Silvaco ATLAS Manual: SOPRA database for Si0.85Ge0.15’, User's Manual (Silvaco Inc., Santa Clara, CA, 2013), p. 1487.
    37. 37)
      • 37. Sze, S., Lee, M.: ‘Chapter 2: energy bands and carrier concentration in thermal equilibrium’, in Singleton, K. (Ed.): ‘Semiconductor devices physics and technology’ (John Wiley and Sons Inc., New York, USA, 2012, 3rd edn.), pp. 3435.
    38. 38)
      • 38. Jensen, N., Rau, U., Hausner, R.M., et al: ‘Recombination mechanisms in amorphous silicon/crystalline silicon heterojunction solar cells’, J. Appl. Phys., 2000, 87, (5), pp. 26392645.

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