Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Effect of Work Function of Zn-doped ITO Thin Films on Characteristics of Silicon Heterojunction Solar Cells

실리콘 이종접합 태양전지 특성에 대한 Zn 도핑된 ITO 박막의 일함수 효과

  • Lee, Seung-Hun (Department of Materials Science and Engineering, Korea University) ;
  • Tark, Sung-Ju (Department of Materials Science and Engineering, Korea University) ;
  • Choi, Su-Young (Department of Materials Science and Engineering, Korea University) ;
  • Kim, Chan-Seok (Department of Materials Science and Engineering, Korea University) ;
  • Kim, Won-Mok (Electronic materials center, Korea Institute of Science and Technology) ;
  • Kim, Dong-Hhwan (Department of Materials Science and Engineering, Korea University)
  • 이승훈 (고려대학교 신소재공학과) ;
  • 탁성주 (고려대학교 신소재공학과) ;
  • 최수영 (고려대학교 신소재공학과) ;
  • 김찬석 (고려대학교 신소재공학과) ;
  • 김원목 (한국과학기술연구원 전자재료연구센터) ;
  • 김동환 (고려대학교 신소재공학과)
  • Received : 2011.07.04
  • Accepted : 2011.08.11
  • Published : 2011.09.27
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Abstract

Transparent conducting oxides (TCOs) used in the antireflection layer and current spreading layer of heterojunction solar cells should have excellent optical and electrical properties. Furthermore, TCOs need a high work function over 5.2 eV to prevent the effect of emitter band-bending caused by the difference in work function between emitter and TCOs. Sn-doped $In_2O_3$ (ITO) film is a highly promising material as a TCO due to its excellent optical and electrical properties. However, ITO films have a low work function of about 4.8 eV. This low work function of ITO films leads to deterioration of the conversion efficiency of solar cells. In this work, ITO films with various Zn contents of 0, 6.9, 12.7, 28.8, and 36.6 at.% were fabricated by a co-sputtering method using ITO and AZO targets at room temperature. The optical and electrical properties of Zn-doped ITO thin films were analyzed. Then, silicon heterojunction solar cells with these films were fabricated. The 12.7 at% Zn-doped ITO films show the highest hall mobility of 35.71 $cm^2$/Vsec. With increasing Zn content over 12.7, the hall mobility decreases. Although a small addition of Zn content increased the work function, further addition of Zn content over 12.7 at.% led to decreasing electrical properties because of the decrease in the carrier concentration and hall mobility. Silicon heterojunction solar cells with 12.7 at% Zn-doped ITO thin films showed the highest conversion efficiency of 15.8%.

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References

  1. D. S. Ginley and C. Bright, MRS Bulletin, 25(8), 15 (2000). https://doi.org/10.1557/mrs2000.256
  2. B. O'Regan and M. Gratzel, Nature, 353, 737 (1991). https://doi.org/10.1038/353737a0
  3. M. Gratzel, J. Photochem. Photobiol. Chem., 164, 3 (2004). https://doi.org/10.1016/j.jphotochem.2004.02.023
  4. A. G. Ulyashin, R. Job, M. Scherff, M. Gao, W. R. Fahrner, D. Lyebyedyev, N. Ross and H. -C. Scheer, Thin Solid Films, 403-404, 359 (2002). https://doi.org/10.1016/S0040-6090(01)01569-3
  5. E. Centurioni and D. Iencinella, IEEE Electron Device Lett., 24, 177 (2003). https://doi.org/10.1109/LED.2003.811405
  6. A. Klein, C. Korber, A. Wachau, F. Sauberlich, Y. Gassenbauer, S. P. Harvey, D. E. Proffit and T. O. Mason, Materials, 3, 4892 (2010).
  7. T. Minami, T. Miyata and T. Yamamoto, Surf. Coating. Tech., 108-109, 583 (1998). https://doi.org/10.1016/S0257-8972(98)00592-1
  8. B. L. Gehman, S. Jonsson, T. Rudolph, M. Scherer, M. Weigert and R. Werner, Thin Solid Films, 220, 333 (1992). https://doi.org/10.1016/0040-6090(92)90594-2
  9. D. C. Paine, T. Whitson, D. Janiac, R. Beresford, C. O. Yang and B. Lewis, J. Appl. Phys., 85, 8445 (1999). https://doi.org/10.1063/1.370695
  10. S. H. Lee, T. S. Lee, K. S. Lee, B. Cheong, Y. D. Kim and W. M. Kim, J. Phys. Appl. Phys., 41, 095303 (2008). https://doi.org/10.1088/0022-3727/41/9/095303
  11. T. Minami, T. Yamamoto, H. Toda and T. Miyata, Superficies y Vacio, 9, 65 (1999).
  12. N. Naghavi, C. Marcel, L. Dupont, A. Rougier, J. -B. Leriche and C. Guery, J. Mater. Chem., 10, 2315 (2000). https://doi.org/10.1039/b002094j
  13. F. Wooten, Optical Properties of Solids, P. 9-11, Academic, New York, USA (1981).
  14. B. Stjerna, E. Olsson and C. G. Granqvist, J. Appl. Phys., 76, 3797 (1994). https://doi.org/10.1063/1.357383
  15. T. Minami, H. Sonohara, T. Kakumu and S. Takata, Jpn. J. Appl. Phys., 34, 971 (1995) https://doi.org/10.1143/JJAP.34.L971
  16. R. G. Gordon, MRS Bulletin, 25(8), 52 (2000). https://doi.org/10.1557/mrs2000.151