Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
권호 표지

Effect of Cd Concentration on Characteristics of CdS Thin Films Prepared by Chemical Bath Deposition

화학용액증착법에 의하여 증착된 CdS 박막의 특성에 대한 Cd 농도의 영향

  • Jung, SungHee (Department of Chemical Engineering, Inha University) ;
  • Chung, CheeWon (Department of Chemical Engineering, Inha University)
  • 정성희 (인하대학교 화학공학과) ;
  • 정지원 (인하대학교 화학공학과)
  • Published : 2012.08.10

Abstract

CdS thin films have been widely used as a buffer layer of CIGS semiconductor solar cells to reduce the lattice mismatch between transparent electrode and absorber layer. In order to prepare the CdS films with high transparency and low resistivity, they were deposited by varying Cd concentration with the constant S concentration in the solution using chemical bath deposition method. They were analyzed in terms of structural, optical and electrical properties of CdS films according to the $[S^{2-}]/[Cd^{2+}]$ ratio. In the case of Cd concentration higher than S concectration, CdS thin films were formed mainly by cluster- by-cluster formation due to the homogeneous reaction between Cd and S in the solution. Therefore the grain size increased and the transmittance decreased. On the other hand, in the case of Cd concentration lower than S concentration, CdS films were formed by heterogeneous reaction on the substrate rather than in the solution. The CdS films have the grains with the uniform circular shape of a few hundreds ${\AA}$. As the Cd concentration increased in the solution, the $[S^{2-}]/[Cd^{2+}]$ ratio decreased and the resistivity decreased by the increase in the carrier concentration due to the formation S vacancy by the excess Cd.

Keywords

References

  1. S. M. Kong, Y. Xiao, E. H. Kim, and C. W. Chung, Korean Chem. Eng. Res., 49, 195 (2011).
  2. A. Bollero, M. Andres, C. Garcia, J. Abajo, and M. Gutierrez, Phys. Status Solidi A, 206, 540 (2009). https://doi.org/10.1002/pssa.200824405
  3. U. Rau and H. W. Schock, Appl. Phys. A, 69, 131 (1999). https://doi.org/10.1007/s003390050984
  4. N. Fujimura, T. Nishihara, S. Goto, J. Xu, and T. Ito, J. Cryst. Growth, 130, 269 (1993). https://doi.org/10.1016/0022-0248(93)90861-P
  5. S. M. Kong, Y. Xiao, E. H. Kim, and C. W. Chung, J. Nanosci. Nanotechnol,, 11, 1 (2011). https://doi.org/10.1166/jnn.2011.3839
  6. K. S. Ramaiah, R. D. Pilkington, A. E. Hill, R. D. Tomlinson, and A. K. Bhatmagar, Mater. Chem. and Phys., 68, 22 (2001). https://doi.org/10.1016/S0254-0584(00)00281-9
  7. W. C. Song, J. Kor. Inst. Surf. Eng., 38, 112 (2005).
  8. M. A. Martinez, C. Guillen, and J. Herrero, Appl. Surf. Science., 136, 8 (1998). https://doi.org/10.1016/S0169-4332(98)00331-6
  9. A. Y. Jaber, S. N. Alamri, M. S. Aida, M. Benghanem, and A. A. Abdelaziz, J. Alloy. Comp., 529, 63 (2012). https://doi.org/10.1016/j.jallcom.2012.03.093
  10. L. Wenyi, C. Zun, C. Qiulong, and Z. Zhibin, Materials Lett., 59, 1 (2005). https://doi.org/10.1016/j.matlet.2004.04.008
  11. H. Moualkia, S. Hariech, M. S. Aida, N. Attaf, and E. L. Laifa, J. Phys. D : Appl. Phys., 42, 1 (2009).
  12. W. C. Song, J. Kor. Inst. Surf. Eng., 41, 1 (2008)
  13. S. Mathew, P. S. Mukerjee, and K. P. Vijauakumar, Thin Solid Films, 254, 278 (1995). https://doi.org/10.1016/0040-6090(94)06257-L
  14. M. Tsuji, T. Ararmoto, H. Ohyama, T. Hibino, and K. Omura, J. Cryst. Growth, 214, 1142 (2000).
  15. S. G. Hur, H. J. Cho, K. W. Park, J. K. Ahn, and S. G. Yoon, J. Kor. Ins. Elec. and Elec Mater. Eng., 22, 1023 (2009).
  16. T. Chu, S. Chu, N. Shultz, C. Wang, and C. Wu, J. Electrochem. Soc., 139, 2443 (1992). https://doi.org/10.1149/1.2221246
  17. H. Metin, M. Ari, S. Erat, S. Durms, M. Bozoklu, and A. Braun, J. Mater. Res., 25, 189 (2010). https://doi.org/10.1557/JMR.2010.0025
  18. A. Kylner, J. Appl. Phys. 85, 6858 (1999). https://doi.org/10.1063/1.370204
  19. H. Khallaf, I. O. Oladeji, G. Chai, and L. Chow, Thin Solid Films, 516, 7306 (2008). https://doi.org/10.1016/j.tsf.2008.01.004
  20. F. Liu, Y. Lai, J. Liu, B. Wang, S. Kuang, Z. Zhang, J. Li, and Y. Liu, J. alloy and compounds, 493, 305 (2010). https://doi.org/10.1016/j.jallcom.2009.12.088
  21. J. H. Lee, J. KIEEME, 21, 620 (2008).
  22. O. Z. Angel and R. L. Morales, Physical Review B, 62, 13064 (2000). https://doi.org/10.1103/PhysRevB.62.13064