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The Characteristics of Amorphous-Oxide-Semiconductor Thin-Film-Transistors According to the Active-Layer Structure

능동층 구조에 따른 비정질산화물반도체 박막트랜지스터의 특성

  • Lee, Ho-Nyeon (Department of Display and Electronic Information Engineering, Soonchunhyang University)
  • 이호년 (순천향대학교 전자정보공학과)
  • Published : 2009.07.31

Abstract

Amorphous indium-gallium-zinc-oxide thin-film-transistors (TFTs) were modeled successfully. Dependence of TFT characteristics on structure, thickness, and equilibrium electron-density of the active layer was studied. For mono-active-layer TFTs, a thinner active layer had higher field-effect mobility. Threshold voltage showed the smallest absolute value for the 20 nm active-layer. Subthreshold swing showed almost no dependence on active-layer thickness. For the double-active-layer case, better switching performances were obtained for TFTs with bottom active layers with higher equilibrium electron density. TFTs with thinner active layers had higher mobility. Threshold voltage shifted in the minus direction as a function of the increase in the thickness of the layer with higher equilibrium electron-density. Subthreshold swing showed almost no dependence on active-layer structure. These data will be useful in optimizing the structure, the thickness, and the doping ratio of the active layers of oxide-semiconductor TFTs.

비정질 인듐-갈륨-아연 산화물 박막트랜지스터를 모델링 하여서, 능동층의 구조, 두께, 평형상태의 전자밀도에 대응하는 박막트랜지스터의 특성을 연구하였다. 단일 능동층 박막트랜지스터의 경우, 능동층이 얇을 때 높은 전계효과이동도를 보였다. 문턱전압의 절대값은 능동층의 두께가 20 nm일 때 최저치를 보였으며, 문턱전압이하 기울기는 두께에 대한 의존성을 보이지 않았다. 복층구조 능동층의 경우, 하부의 능동층이 높은 평형상태 전자밀도를 가질 때보다 우수한 스위칭 특성을 보였다. 이 경우에도 능동층의 두께가 얇을 때에 높은 전계효과 이동도를 보였다. 높은 평형상태 전자밀도의 능동층의 두께를 증가시키면 문턱전압은 음의 방향으로 이동하였다. 문턱전압이하 기울기는 능동층의 구조에 대하여 특별한 의존성을 보이지 않았다. 이상과 같은 데이터는 산화물반도체 박막트랜지스터 능동층의 구조, 두께, 도핑비율을 최적화함에 효과적으로 사용될 것으로 기대된다.

Keywords

References

  1. G. F. Bosen and J. J. Jacobs, "ZnO Field-Effect Transistor", Proc. IEEE, pp. 2094-2095, 1968. https://doi.org/10.1109/PROC.1968.6813
  2. T. Hirao, M. Furuta, H. Furuta, T. Matsuda, T. Hiramatsu, H. Hokari, M. Yoshida, H. Ishii and M. Kakegawa, "Novel top-gate zinc oxide thin-film transistors (ZnO TFTs) for AMLCDs", J. Soc. Information Display, vol. 15, pp. 17-22, 2007. https://doi.org/10.1889/1.2451545
  3. P. Carcia, R. McLean and M. Reilly, "Oxide engineering of ZnO thin-film transistors for flexible electronics", J. Soc. for Information Display, vol. 13, pp. 547-554, 2005. https://doi.org/10.1889/1.2012634
  4. N. L. Dehuff, E. S. Kettenring, D. Hong, H. Q. Chang and J. J. Wager, "Transparent thin-film transistors with zinc indium oxide channel laer", Journal of Applied Physics. vol. 97, pp. 064505, 2005. https://doi.org/10.1063/1.1862767
  5. W. B. Jackson, G. S. Herman, R. L. Hoffmann, C. Taussig, S. Braymen, F. Jeffery and J. Hauschildt, "Zinc tin oxide transistors on flexible substrates", J. Non-Cryst. Solids, vol. 352, pp. 1753-1755, 2006. https://doi.org/10.1016/j.jnoncrysol.2005.11.080
  6. K. Nomura, H. Ohta, K. Ueda, T. Kamiya, M. Hirano and H. Hosono, "All oxide transparent MISFET using high-k dielectrics gates", Microelectronic Engineering, vol. 72, pp. 294-298, 2004. https://doi.org/10.1016/j.mee.2004.01.007
  7. K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano and H. Hosono, "Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors", Nature, vol. 432, pp. 488-492, 2004. https://doi.org/10.1038/nature03090
  8. H. Hosono, "Ionic amorphous oxide semiconductors: Material design, carrier transport, and device application", J. Non-Cryst. Solids, vol. 352, pp. 851-858, 2006. https://doi.org/10.1016/j.jnoncrysol.2006.01.073
  9. J. K. Jeong, H. W. Yang, J. H. Jeong, Y. G. Mo and H. D. Kim, "Origin of threshold voltage instability in indium-gallium-zinc oxide thin film transistors", Appl. Phys. Lett., vol. 93, pp. 123508, 2008. https://doi.org/10.1063/1.2990657
  10. J. M. Lee, I. T. Cho, J. H. Lee and H. I. Kwon, "Bias-stress-induced stretched-exponential time dependence of threshold voltage shift in InGaZnO thin film transistors", Appl. Phys. Lett., vol. 93, pp. 093504, 2008. https://doi.org/10.1063/1.2977865
  11. I. Titkov, I. Pronin, I. Liniichuk and I. Grekhov, "Transparent ferroelectric field effect transistors with a single-crystal $SnO_{2}$ channel", Integr. Ferroelectr. vol. 72, pp. 53-60, 2005. https://doi.org/10.1080/10584580500312818
  12. D. Cho, Sh. Yang, C. Byun, J. Shin, M. Ryu, S. Park, C. Hwang, S. Chung, W. Cheong, S. Yoon and H. Chu, "Transparent Al–Zn–Sn–O thin film transistors prepared at low temperature", Appl. Phys. Lett., vol. 93, pp. 142111, 2008. https://doi.org/10.1063/1.2998612
  13. H. D. Kim, J. K. Jeong, Y. G. Mo and H. K. Chung, "Oxide TFT as an Emerging Technology for Next Generation Display", Proc. Int. Meeting on Information Display, pp. 119-122, 2008.
  14. J. H. Lee, D. H. Kim, D. J. Yang, S. Y. Hong, K. S. Yoon, P. S. Hong, C. O. Jeong, H. S. Park, S. Y. Kim, S. K. Lim, S. S. Kim, K. S. Son, T. S Kim, J. Y Kwon and S. Y. Lee, "World's Largest (15-inch) XGA AMLCD Panel Using IGZO Oxide TFT", Soc. Information Display 2008 Int. Symp. Digest of Tech. Papers, pp. 625-628, 2008.
  15. ATLAS User's Manual (Silvaco International, Santa Clara, California, 2007).
  16. A. Ohtomo, K. Tamura, K. Saikusa, K. Takahashi, T. Makino, Y. Segawa, H. Koinuma and M. Kawasaki, "Single crystalline ZnO films grown on lattice-matched $ScAlMgO_{4}$(0001) substrates", Appl. Phys. Lett., vol. 75, pp. 2635-2637, 1999. https://doi.org/10.1063/1.125102
  17. K. B. Sundaram and A. Khan, "Work function determination of zinc oxide films", J. Vac. Sci. Technol. A, vol. 15, pp. 428-430, 1997. https://doi.org/10.1116/1.580502
  18. Rode, D. L., Semiconductors and Semimetals, R. K. Willardson and A. C. Beer, eds., Academic Press, N.Y., vol. 10, p. 1, 1975.
  19. H. H. Hsieh, T. Kamiya, K. Nomura, H. Hosono and C. C. Wu, "Modeling of amorphous InGaZnO4 thin film transistors and their subgap density of states", Appl. Phys. Lett., vol. 92, pp. 133503, 2008. https://doi.org/10.1063/1.2857463
  20. L. Bornstein, in Seimiconductors, edited by O. Medelung (Springer, Berlin, 1998), vol III-17, pp. 35-115.
  21. P. Barquinha, A. Pimentel, A. Marques, L. Pereira, R. Martins, E. Fortunato, "Effect of UV and visible light radiation on the electrical performances of transparent TFTs based on amorphous indium zinc oxide", J. Non-Cryst. Solids, vol. 352, pp. 1756- 1760, 2006. https://doi.org/10.1016/j.jnoncrysol.2006.01.068
  22. M. S. Grover, P. A. Hersh, H. Q. Chiang, E. S. Kettenring, J. F. Wager and D. A. Keszler, "Thin-film transistors with transparent amorphous zinc indium tin oxide channel layer", J. Phys. D: Appl. Phys., vol. 40, pp. 1335-1338, 2007. https://doi.org/10.1088/0022-3727/40/5/004