Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
권호 표지

Characteristics of Al-doped ZnO thin films prepared by sol-gel method

졸-겔법으로 제조한 Al-doped ZnO 박막의 특성에 관한 연구

  • Kim, Yong-Nam (Korea Testing Laboratory Material Analysis Team) ;
  • Lee, Seoung-Soo (Korea Testing Laboratory Material Analysis Team) ;
  • Song, Jun-Kwang (Korea Testing Laboratory Material Analysis Team) ;
  • Noh, Tai-Min (School of Material Science of Engineering, Pusan National University) ;
  • Kim, Jung-Woo (School of Material Science of Engineering, Pusan National University) ;
  • Lee, Hee-Soo (School of Material Science of Engineering, Pusan National University)
  • 김용남 (한국산업기술시험원 재료평가팀) ;
  • 이승수 (한국산업기술시험원 재료평가팀) ;
  • 송준광 (한국산업기술시험원 재료평가팀) ;
  • 노태민 (부산대학교 재료공학부) ;
  • 김정우 (부산대학교 재료공학부) ;
  • 이희수 (부산대학교 재료공학부)
  • Published : 2008.02.29
Download PDF
⟨ Previous Next ⟩

Abstract

AI-doped ZnO(AZO) thin films have been fabricated on glass substrate by sol-gel method, and the effect of Al precursors and post-annealing temperature on the characteristics of AZO thin films was investigated. The sol was prepared with zinc acetate, EtOH, MEA and Al precursors. In order to dope Al in ZnO, two types of aluminum nitrate and aluminum chloride were used as Al precursor. Zinc concentration was 0.5 mol/l and the content of Al precursor was 1 at% of Zn in the sol. The sol was spin-coated on glass substrate, and the coated films were annealed at 550ue for 2 hand were post-annealed at temperature ranges of $300{\sim}500^{\circ}C$ for 2 h in reducing atmosphere ($N_2/H_2$= 9/1). Structural, electrical and optical propertis of the fabricated AZO thin films were analyzed by XRD, FE-SEM, AFM, hall effect measurement system and UV-visible spectroscopy. Optical and electrical properties of AZO thin films prepared with aluminum nitrate as Al precursor were better than those of films prepared with aluminum chloride. The electrical resistivity and the optical transmittance of films decreased with increasing post-annealing temperatures. The minimum electrical resistivity of $2{\times}10^{-3}$ and the maximum optical transmittance of 91% were obtained for the AZO thin films post-annealed at $550^{\circ}C\;and\;300^{\circ}C$, respectively.

졸-겔 공정을 이용하여 유리기판 위에 Al-doped ZnO(AZO) 박막을 제조하였고, AZO 박막의 특성에 대하여 Al 전구체 종류 및 post-annealing 온도가 미치는 영향에 대하여 고찰하였다. AZO 박막 제조용 졸은 zinc acetate, EtOH, MEA 등을 사용하여 제조하였고, Al doping 을 위한 전구체로는 aluminum nitrate 와 aluminum chloride 를 사용하였다. Sol 내의 Zn 농도는 0.5 mol/l 로 하였고, Al doping 양은 Zn 대비 1 at%로 고정하였다. 유리기판 위에 졸을 spin-coating 한 후 $550^{\circ}C$에서 2 시간 동안 열처리한 후, $N_2$와 $H_2$의 비가 9 : 1인 환원 분위기 내에서 $300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C$인 온도에서 2시간 동안 post-annealing을 진행하였다. 제조된 AZO 박막의 구조적, 전기적, 광학적 특성은 XRD, FE-SEM, AFM, Hall effect measurement system 및 UV-Visible spectroscopy를 이용하여 분석하였다. Al 전구체로서 aluminum nitrate 를 사용한 경우가 aluminum chloride 를 사용하여 제조한 AZO 박막보다 우수한 광학적, 전기적 특성을 나타내었으며, post-annealing 온도가 증가함에 따라 비저항과 투과율은 감소하였다. $500^{\circ}C$에서 post-annealing한 AZO 박막의 전기비저항 값은 $2{\times}10^{-3}{\Omega}{\cdot}cm$이었고, 투과율은 $300^{\circ}C$에서 91%로 가장 높게 나타났다.

Keywords

References

  1. P. Nunes, D. Costa, E. Fortunato and R. Martins, "Performances presented by zinc oxide thin films deposited by R.F. magnetron sputtering", Vacuum 64 (2002) 293 https://doi.org/10.1016/S0042-207X(01)00323-2
  2. P. Nunes, E. Fortunato, P. Tonello, F. Braz Fernandes, P. Vilarinho and R. Martins, "Effect of different dopant elements on the properties of ZnO thin films", Vaccum 64 (2002) 281 https://doi.org/10.1016/S0042-207X(01)00322-0
  3. S.B. Majumder, M. Jain, P.S. Dobal and R.S. Katiyar, "Investigations on solution derived aluminum doped zinc oxide thin films", Mater. Sci. and Eng. B 103[1] (2003) 16 https://doi.org/10.1016/S0921-5107(03)00128-4
  4. Oliver Kluth, Gunnar Schöpe, Bernd Rech, Richard Menner, Mike Oertel, Kay Orgassa and Hans Werner Schock, "Comparative material study on RF and DC magnetron sputtered ZnO : Al films", Thin Solid Films 502 (2006) 311 https://doi.org/10.1016/j.tsf.2005.07.313
  5. Andreas Pflug, Volker Sittinger, Florian Ruske, Bernd Szyszka and Georg Dittmar, "Optical characterization of aluminum-doped zinc oxide films by advanced dispersion theories", Thin Solid Films 455-456 (2004) 201 https://doi.org/10.1016/j.tsf.2004.01.006
  6. M.A. Kaid and A. Ashour, "Preparation of ZnO-doped Al films by spray pyrolysis technique", Appl. Surf. Sci. 253 (2007) 3029 https://doi.org/10.1016/j.apsusc.2006.06.045
  7. T. Schuler and M.A. Aegerter, "Optical, electrical and structural properties of sol-gel ZnO : Al coatings", Thin Solid Films 351 (1999) 125 https://doi.org/10.1016/S0040-6090(99)00211-4
  8. Radhouane Bel Hadh Tahar, "Structural and electrical properties of aluminum-doped zinc oxide films prepared by sol-gel process", J. Europe. Ceram. Soc. 25 (2005) 3301 https://doi.org/10.1016/j.jeurceramsoc.2004.08.028
  9. S.Y. Kuo, W.C. Chen, F.I. Lai, C.P. Cheng, H.C. Kuo, S.C. Wang and W.F. Hsieh, "Effects of doping concentration and annealing temperature on properties of highly-oriented Al-doped ZnO films", J. Cryst. Growth 287 (2006) 78 https://doi.org/10.1016/j.jcrysgro.2005.10.047
  10. Keh-moh Lin and Paijay Tsai, "Parametric study on preparation and characterization of ZnO : Al films by sol-gel methos for solar cell", Materials Science and Engineering B 139 (2007) 81 https://doi.org/10.1016/j.mseb.2007.01.050
  11. Keh-moh Lin and Paijay Tsai, "Growth mechanism and Characterization of ZnO : Al multi-layered thin films by sol-gel technique", Thin Solid Films 515 (2007) 8601 https://doi.org/10.1016/j.tsf.2007.04.012
  12. Hong-ming Zhou, Dan-qing Yi, Zhi-ming Yu, Lai-rong Xiao and Jian Li, "Preparation of aluminum doped zinc oxide films and the study of their microstructure, electrical and optical properties", Thin Solid Films 515 (2007) 6909 https://doi.org/10.1016/j.tsf.2007.01.041
  13. Xin. Chen, Wenjie Guan, Guojia Fang and X.Z. Zhao, "Influence of substrate temperature and post-treatment on the properties of ZnO : Al thin films prepared by pulsed laser deposition", Appl. Surf. Sci. 252, (2005) 1561 https://doi.org/10.1016/j.apsusc.2005.02.137
  14. A. Martin, J.P. Espinos, A. Justo, J.P. Holgado, F. Yubero and A.R. Gonzales-Elipe, "Prerparation of transparent and conductive Al-dopes ZnO thin films by ECR plasma enhanced CVD", Surface and Coatings Technology 151-152 (2002) 289 https://doi.org/10.1016/S0257-8972(01)01609-7
  15. D.R. Sahu, S.-Y. Lin and J.-L. Huang, "Investigation of conductive and transparent Al-doped ZnO/Ag/Al-doped ZnO multilayer coatings by electron beam evaporation", Thin Solid Films (2007)
  16. Y.-S. Kim and W.-P. Tai, "Electrical and optical properties of Al-doped ZnO thin films by sol-gel process", Appl. Surf. Sci. 253 (2007) 4911 https://doi.org/10.1016/j.apsusc.2006.10.068
  17. M. Ohyama, H. Kozuka and T. Yoko, "Sol-gel preparation of ZnO films with extremely preffered orienrarion along (002) plane from zinc acetate solution", Thin Solid Films 306[1] (1997) 78 https://doi.org/10.1016/S0040-6090(97)00231-9
  18. S.M. Hyun, K. Hong and B.H. Kim, "Preparation and characterization of Al-doped ZnO transparent conducting thin film by sol-gel processing", J. Kor. Ceram. Soc. 33 (1996) 149
  19. S.-B. Ko, M.-S. Choi, H. Ko, C.-S. Lee, W.-P. Tai, S.-J. Suh and Y.-S. Kim, "Optical and electrical properties with various post-heating temperatures in the Al-doped ZnO thin films by sol-gel process", J. Kor, Ceram. Soc. 41[10] (2004) 742 https://doi.org/10.4191/KCERS.2004.41.10.742
  20. M.N. Islam, M.O. Hakim and H. Rah, "The effect of deposition variables on sparay-deposited ZnO thin films prepared by RF magnetron sputtering for transparent electrode applications", J. Appl. Phys. 55(4) (1984) 1029 https://doi.org/10.1063/1.333196
  21. H. Gomez-Pozos, A. Maldonado and M. de la L. Olvera, "Effect of the [Al/Zn] ratio in the starting solution and deposition temperature on the physical properties of sprayed ZnO : Al thin films", Materials Letters 61 (2007) 1460 https://doi.org/10.1016/j.matlet.2006.07.053
  22. P. Nunes, E. Fortunato and R. Martins, "Influence of the post-treatment on the properties of ZnO thin films", Thin Solid Films 383 (2001) 277 https://doi.org/10.1016/S0040-6090(00)01577-7