반도체디스플레이기술학회지 (Journal of the Semiconductor & Display Technology)

한국반도체디스플레이기술학회 (The Korean Society Of Semiconductor & Display Technology)
권호 표지

AZO 박막의 표면 거칠기에 따른 OLED 소자의 특성

Effect of surface roughness of AZO thin films on the characteristics of OLED device

  • 이봉근 (한국기술교육대학교 신소재공학과) ;
  • 이규만 (한국기술교육대학교 신소재공학과)
  • Lee, B.K. (Dept. of Materials Engineering, Korea University of Technology and Education) ;
  • Lee, K.M. (Dept. of Materials Engineering, Korea University of Technology and Education)
  • 투고 : 2010.11.25
  • 심사 : 2010.12.17
  • 발행 : 2010.12.31
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

We have investigated the effect of surface roughness of TCO substrate on the characteristics of OLED (organic light emitting diodes) devices. In order to control the surface roughness of AZO thin films, we have processed photo-lithography and reactive ion etching. The micro-size patterned mask was used, and the etching depth was controlled by changing etching time. The surface morphology of the AZO thin film was observed by FESEM and atomic force microscopy (AFM). And then, organic materials and cathode electrode were sequentially deposited on the AZO thin films. Device structure was AZO/${\alpha}$-NPD/DPVB/$Alq_3$/LiF/Al. The DPVB was used as a blue emitting material. The electrical characteristics such as current density vs. voltage and luminescence vs. voltage of OLED devices were measured by using spectrometer. The current vs. voltage and luminance vs. voltage characteristics were systematically degraded with increasing surface roughness. Furthermore, the retention test clearly presented that the reliability of OLED devices was directly influenced with the surface roughness, which could be interpreted in terms of the concentration of the electric field on the weak and thin organic layers caused by the poor step coverage.

키워드

참고문헌

  1. S. Kawamura, J. Sakurai, M. Nakano, and M. Takagi "Recrystallization of Si on amorphous substrates by doughnut-shaped cw Ar laser beam", Appl. Phys. Lett. 40, pp. 394, 1982. https://doi.org/10.1063/1.93114
  2. J. Hinze, and K. Ellmer, "In situ measurement of mechanical stress in polycrystalline zinc-oxide thin films prepared by magnetron sputtering", J. Appl. Phys., 88, pp. 2443, 2000. https://doi.org/10.1063/1.1288162
  3. G.A. Hirata, J. McKittrick, T. Cheeks, J.M. Siqueiros, J.A. Diaz, O. Contreras and O.A. Lopez, "Synthesis and optoelectronic characterization of gallium doped zinc oxide transparent electrodes", Thin Solid Films , 288, pp. 29, 1996. https://doi.org/10.1016/S0040-6090(96)08862-1
  4. T. Sasabayashi, N. Ito, E. Nishimura, M. Kon, P. K. Song, K. Utsumi, A. Kaijo, and Y. Shigesato, "Comparative study on structure and internal stress in tin-doped indium oxide and indium-zinc oxide films deposited by r.f. magnetron sputtering," Thin Solid Films, 445, pp. 219, 2003. https://doi.org/10.1016/j.tsf.2003.08.047
  5. T. Moriga, M. Mikawa, Y. Sakakibara, Y. Misaki, K. I. Murai, I. Nakabayashi, K. Tominaga, and J. B. Metson, "Effects of introduction of argon on structural and transparent conducting properties of ZnO-$In_{2}O_{3}$ thin films prepared by pulsed laser deposition", Thin Solid Films, 486, pp. 53, 2005. https://doi.org/10.1016/j.tsf.2004.11.241
  6. F. K. Shan and Y. S. Yu, "Band gap energy of pure and Al-doped ZnO thin films", J. European Ceram. Soc., 24, pp. 1869, 2004. https://doi.org/10.1016/S0955-2219(03)00490-4
  7. J. Hu and R. G. Gordon, "Textured aluminum-doped zinc oxide thin films from atmospheric pressure chemical-vapor deposition", J. Appl. Phys., 71, pp. 880, 1992. https://doi.org/10.1063/1.351309
  8. X. Jiang, F. L. Wong, M. K. Fung, and S. T. Lee, "Aluminum-doped zinc oxide films as transparent conductive electrode for organic light-emitting devices", Appl. Phys. Lett., 83, pp. 1875, 2002.
  9. Y. Choi, "Growth and Preferred Orientation of ITO Thin Film Deposited by D.C. Magnetron Sputtering", J. Kor. Inst. Met. & Mater., 45, pp. 559-586, 2007.
  10. H. Ko, W. P. Tai, K. C. Kim, S. H. Kim, S. J. Suh, and Y. S. Kim, "Growth of Al-doped ZnO thin films by pulsed DC magnetron sputtering," J. Cryst. Growth, 277, pp. 352,2005. https://doi.org/10.1016/j.jcrysgro.2005.01.061
  11. C. H. Jonda, A. B. R. Mayer, and U. Stolz, "Surface roughness effects and their influence on the degradation of organic light emitting devices," J. Mat. Sci., 35, pp. 5645. 2000 https://doi.org/10.1023/A:1004842004640
  12. B. Y. Oh, M. C. Jeong, W. Lee, and J. M. Myoung, "Properties of transparent conductivw ZnO:Al films prepared by co-sputtering," J. Cryst. Growth, 274, pp. 453, 2005. https://doi.org/10.1016/j.jcrysgro.2004.10.026
  13. X. T. Hao, L. W. Tan, K. S. Ong, and F. Zhu, "High-performance low-temperature transparent conducting aluminum doped ZnO thin films and applications," J. Cryst. Growth, 287, pp. 44, 2006. https://doi.org/10.1016/j.jcrysgro.2005.10.040