Journal of the Korea Institute of Information and Communication Engineering (한국정보통신학회논문지)

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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Effects of Doping Concentrations and Annealing Temperatures on the Electrical and Optical Properties of Ga-doped ZnO Thin Films by Sol-gel Method

Sol-gel 법으로 제작한 Ga-doped ZnO 박막의 도핑 농도와 열처리 온도가 전기적 및 광학적 특성에 미치는 효과

  • 강성준 (전남대학교 전기 및 반도체 공학과) ;
  • 정양희 (전남대학교 전기 및 반도체 공학과)
  • Received : 2011.10.20
  • Accepted : 2011.11.22
  • Published : 2012.03.31
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Abstract

We fabricated Ga doped ZnO (GZO) thin films on the glass substrate (Eagle 2000) with various of Ga doping concentration and annealing temperatures using sol-gel method, electrical and optical properties were investigated. When the GZO thin films doped with 1 mol% of Ga and annealed at $600^{\circ}C$, the excellent (002) orientation was observed. In the results of Hall measurement, carrier concentration decreased and resistivity increased due to segregation effect with increasing of the Ga doping concentration. The largest carrier concentration and lowest resistivity were $9.13{\times}10^{18}cm^{-3}$ and $0.87{\Omega}cm$, respectively, in the GZO thin films doped with 1 mol% Ga and annealed at $600^{\circ}C$. All films is higher than 80 % in the visible light region. Energy band gap narrowing due to Burstein-Moss effect was observed with increasing of Ga doping concentration from 1 to 4 mol%.

Sol-gel 법으로 Eagle 2000 유리 기판 위에 Ga 도핑 농도와 열처리 온도에 따른 GZO 박막을 제작하여, 전기적 및 광학적 특성을 조사하였다. 1 mol% Ga 이 도핑되고 $600^{\circ}C$에서 열처리한 GZO 박막에서 가장 우수한 (002) 배향성이 관찰되었다. Hall 측정 결과, Ga 도핑 농도가 증가함에 따라 segregation 효과로 인한 캐리어 농도의 감소와 비저항 값의 증가가 관찰되었다. 1 mol% Ga 이 도핑되고 $600^{\circ}C$에서 열처리한 GZO 박막에서 가장 큰 캐리어 농도($9.13{\times}10^{18}cm^{-3}$)와 가장 낮은 비저항 ($0.87{\Omega}cm$) 값을 나타내었다. 모든 박막은 가시광 영역에서 약 80 % 이상의 투과율을 보였으며, Ga 농도가 1 에서 4 mol% 로 증가함에 따라 에너지 밴드 갭이 좁아지는 Burstein-Moss 효과가 관찰되었다.

Keywords

References

  1. G.P.Crawford, Flexible Flat Panel Displays, NJ. U.S.A.: John Wiley & Sons Inc., 2005.
  2. H.Ohta and H.Hosono, "Transparent oxide optoelectronics", Materials Today, vol. 7, pp. 42-51, 2004.
  3. B.D.Ahn, J.H.Kim, H.S.Kang, C.H.Lee, S.H.Oh, K.W.Kim, G.E.Jang and S.Y.Lee, "Thermally stable, highly conductive, and transparent Ga-doped ZnO thin films", Thin Solid Films, vol. 516, pp. 1382-1385, 2008. https://doi.org/10.1016/j.tsf.2007.03.072
  4. C.Guillen and J.Herrero, "High conductivity and transparent ZnO:Al films prepared at low temperature by DC and RF magnetron sputtering", Thin Solid Films, vol. 515, pp. 640-643, 2006. https://doi.org/10.1016/j.tsf.2005.12.227
  5. V.Bhosle, A.Tiwari and J.Narayan, "Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO", Appl. Phys. Lett., vol. 88, pp. 032106-032108, 2006. https://doi.org/10.1063/1.2165281
  6. K.Yim, H.W.Kim and C.Lee, "Effects of annealing on structure, resistivity and transmittance of Ga doped ZnO films", Mater. Sci. Technol., vol. 23, pp. 108-112, 2007. https://doi.org/10.1179/174328407X158514
  7. O.Nakagawara, Y.Kishimoto, H.Seto, Y.Koshido, Y.Yoshino and T.Makino, "Moisture-resistant ZnO transparent conductive films with Ga heavy doping", Appl. Phys. Lett., vol. 89, pp. 091904-091906, 2006 https://doi.org/10.1063/1.2337542
  8. X.Yu, J.Ma, F.Ji, Y.Wang, C.Cheng and H.Ma, "Thickness dependence of properties of ZnO:Ga films deposited by rf magnetron sputtering", Appl. Surf. Sci., vol. 245, pp. 310-315, 2005. https://doi.org/10.1016/j.apsusc.2004.10.022
  9. H.H.Shin, Y.H.Joung and S.J.Kang, "Influence of the Substrate Temperature on the Optical and Electrical Properties of Ga-doped ZnO Thin Films Fabricated by Pulsed Laser Deposition," J. Mater. Sci. : Mater. Electron, vol. 20, pp. 704-708, 2009. https://doi.org/10.1007/s10854-008-9788-9
  10. J.J.Robbins, J.Harvey, J.Leaf, C.Fry and C.A.Wolden, "Transport phenomena in high performance nanocrystalline ZnO:Ga films deposited by plasma-enhanced chemical vapor deposition", Thin Solid Films, vol. 473, pp. 35-40, 2005. https://doi.org/10.1016/j.tsf.2004.06.154
  11. K.Y.Cheong, N.Muti and S.R.Ramanan, "Electrical and optical studies of ZnO:Ga thin films fabricated via the sol-gel technique", Thin Solid Films, vol. 410, pp.142-146, 2002. https://doi.org/10.1016/S0040-6090(02)00286-9
  12. P.K.Nayak, J.H.Yang, J.W.Kim, S.J.Chung, J.W.Jeong, C.H.Lee and Y.T.Hong, "Spin-coated Ga-doped ZnO transparent conducting thin films for organic light-emitting diodes", J. Appl. Phys., vol. 42, pp. 035102-035107, 2009. https://doi.org/10.1088/0022-3727/42/3/035102
  13. N.Fujimura, T.Nishihara, S.Goto, J.Xu and T.Ito, "Control of preferred orientation for ZnOx films control of self-texture", J. Cryst. Growth, vol. 130, pp. 269-279, 1993. https://doi.org/10.1016/0022-0248(93)90861-P
  14. Z.Q.Xu, H.Deng, Y.Li and H.Cheng, "Al-doping effects on structure, electrical and optical properties of c-axis-oriented ZnO:Al thin films", Mater. Sci. Semicond. Process, vol. 9, pp. 132-135, 2006. https://doi.org/10.1016/j.mssp.2006.01.082
  15. M.J.Alam and D.C.Cameron, "Preparation and properties of transparent conductive Aluminum-doped zinc oxide thin films by sol-gel process," J. Vac. Sci. Technol. A, vol. 19, pp. 1642-1645, 2001. https://doi.org/10.1116/1.1340659
  16. Q.B.Ma, Z.Z.Ye, H.P.He, L.P.Zhu, J.R.Wang and B.H.Zhao, "Structural, electrical, and optical properties of transparent conductive ZnO:Ga films prepared by DC reactive magnetron sputtering", J. Crystal. growth, vol. 304, pp. 64-68, 2007. https://doi.org/10.1016/j.jcrysgro.2007.01.037