Characterization of amorphous zinc tin oxide semiconductors


Amorphous zinc tin oxide (ZTO) was investigated to determine the effect of deposition and postannealing conditions on film structure, composition, surface contamination, and thin-film transistor (TFT) performance. X-ray diffraction results indicated that the ZTO films remain amorphous even after annealing to 600 °C. Rutherford backscattering spectrometry indicated that the bulk Zn:Sn ratio of the sputter-deposited films were slightly tin rich compared to the composition of the ceramic sputter target. X-ray photoelectron spectroscopy indicated that residual surface contamination depended strongly on the sample postannealing conditions where water, carbonate, and hydroxyl species were adsorbed to the surface. Electrical characterization of ZTO TFTs indicated that the best devices had mobilities of 17 cm2/Vs, threshold voltages of −1.5 V, subthreshold slopes of 0.9 V/dec, turn-on voltages of −12 V, and on-to-off ratio of >107. Annealing ZTO in vacuum assisted in the removal of adsorbed species, which may reduce defects in the films and improve device performance.

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  1. 1.

    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 432, 488 (2004).

    CAS  Google Scholar 

  2. 2.

    H. Hosono: Ionic amorphous oxide semiconductors: Material design, carrier transport, and device application. J. Non-Cryst. Solids 352, 851 (2006).

    CAS  Google Scholar 

  3. 3.

    H.Q. Chiang, J.F. Wager, R.L. Hoffman, J. Jeong, and D.A. Keszler: High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer. Appl. Phys. Lett. 86, 013503 (2005).

    Google Scholar 

  4. 4.

    R.L. Hoffman: Effects of channel stoichiometry and processing temperature on the electrical characteristics of zinc tin oxide thin-film transistors. Solid-State Electron. 50, 784 (2006).

    CAS  Google Scholar 

  5. 5.

    S. Seo, C. Choi, Y. Hwang, and B. Bae: High performance solution-processed amorphous zinc tin oxide thin film transistor. J. Phys. D: Appl. Phys. 42, 035106 (2009).

    Google Scholar 

  6. 6.

    D. Hong, H.Q. Chiang, and J.F. Wager: Zinc tin oxide thin-film transistors via reactive sputtering using a metal target. J. Vac. Sci. Technol., B 24, L23 (2006).

    CAS  Google Scholar 

  7. 7.

    D. Hong and J.F. Wager: Passivation of zinc–tin–oxide thin-film transistors. J. Vac. Sci. Technol., B 23, L25 (2005).

    CAS  Google Scholar 

  8. 8.

    Y.J. Chang, D.H. Lee, G.S. Herman, and C.H. Chang: High-performance, spin-coated zinc tin oxide thin-film transistors. Electrochem. Solid-State Lett. 10, H135 (2007).

    CAS  Google Scholar 

  9. 9.

    J.K. Jeong, J.H. Jeong, H.W. Yang, J.S. Park, Y.G. Mo, and H.D. Kim: High performance thin film transistors with cosputtered amorphous indium gallium zinc oxide channel. Appl. Phys. Lett. 91, 113505 (2007).

    Google Scholar 

  10. 10.

    M.G. McDowell and I.G. Hill: Influence of channel stoichiometry on zinc indium oxide thin-film transistor performance. IEEE Trans. Electron Devices 56, 346 (2009).

    Google Scholar 

  11. 11.

    M.G. Kim, H.S. Kim, Y.G. Ha, J. He, M.G. Kanatzidis, A. Facchetti, and T.J. Marks: High-performance solution-processed amorphous zinc-indium-tin oxide thin-film transistors. J. Am. Chem. Soc. 132, 10352 (2010).

    CAS  Google Scholar 

  12. 12.

    K. Satoh, Y. Kakehi, A. Okamoto, S. Murakami, F. Uratani, and T. Yotsuya: Influence of oxygen flow ratio on properties of Zn2SnO4 thin films deposited by RF magnetron sputtering. Jpn. J. Appl. Phys., Part 2 44, L34 (2005).

    CAS  Google Scholar 

  13. 13.

    S. Dutta and A. Dodabalapur: Zinc tin oxide thin film transistor sensor. Sens. Actuators, B 143, 50 (2009).

    Google Scholar 

  14. 14.

    W.B. Jackson, R.L. Hoffman, and G.S. Herman: High-performance flexible zinc tin oxide field-effect transistors. Appl. Phys. Lett. 87, 193503 (2005).

    Google Scholar 

  15. 15.

    M.G. McDowell, R.J. Sanderson, and I.G. Hill: Combinatorial study of zinc tin oxide thin-film transistors. Appl. Phys. Lett. 92, 013502 (2008).

    Google Scholar 

  16. 16.

    W.S. Cheong, S.M. Yoon, J.H. Shin, and C.S. Hwang: Combinatorial approach to the fabrication of zinc-tin-oxide transparent thin-film transistors. J. Korean Phys. Soc. 54, 544 (2009).

    CAS  Google Scholar 

  17. 17.

    M.K. Jayaraj, K.J. Saji, K. Nomura, T. Kamiya, and H. Hosono: Optical and electrical properties of amorphous zinc tin oxide thin films examined for thin film transistor application. J. Vac. Sci. Technol., B 26, 495 (2008).

    CAS  Google Scholar 

  18. 18.

    K. Satoh, Y. Kakehi, A. Okamoto, S. Murakami, K. Moriwaki, and T. Yotsuya: Electrical and optical properties of Al-doped ZnO–SnO2 thin films deposited by RF magnetron sputtering. Thin Solid Films 516, 5814 (2008).

    CAS  Google Scholar 

  19. 19.

    P. Görrn, M. Lehnhardt, T. Riedl, and W. Kowalsky: The influence of visible light on transparent zinc tin oxide thin film transistors. Appl. Phys. Lett. 91, 193504 (2007).

    Google Scholar 

  20. 20.

    S. Seo, Y.H. Hwang, and B.S. Bae: Postannealing process for low temperature processed sol–gel zinc tin oxide thin film transistors. Electrochem. Solid-State Lett. 13, H357 (2010).

    CAS  Google Scholar 

  21. 21.

    S. Jeong, Y. Jeong, and J. Moon: Solution-processed zinc tin oxide semiconductor for thin-film transistors. J. Phys. Chem. C 112, 1108 (2008).

    Google Scholar 

  22. 22.

    Y.H. Kim, K. Ho Kim, M.S. Oh, H.J. Kim, J.I. Han, M.K. Han, and S.K. Park: Ink-jet-printed zinc–tin–oxide thin-film transistors and circuits with rapid thermal annealing process. IEEE Electron Device Lett. 31, 834 (2010).

    Google Scholar 

  23. 23.

    C. Avis and J. Jang: A high performance inkjet printed zinc tin oxide transparent thin-film transistor manufactured at the maximum process temperature of 300°C and its stability test. Electrochem. Solid-State Lett. 14, J9 (2011).

    CAS  Google Scholar 

  24. 24.

    B.N. Pal, B.M. Dhar, K.C. See, and H.E. Katz: Solution-deposited sodium beta-alumina gate dielectrics for low-voltage and transparent field-effect transistors. Nat. Mater. 8, 898 (2009).

    CAS  Google Scholar 

  25. 25.

    T. Kamiya, K. Nomura, and H. Hosono: Present status of amorphous In-Ga-Zn-O thin-film transistors. Sci. Technol. Adv. Mater. 11, 044305 (2010).

    Google Scholar 

  26. 26.

    S.A. Chambers, M.H. Engelhard, V. Shutthanandan, Z. Zhu, T.C. Droubay, L. Qiao, P.V. Sushko, T. Feng, H.D. Lee, T. Gustafsson, A.B. Shah, J.M. Zuo, and Q.M. Ramasse: Instability, intermixing and electronic structure at the epitaxial LaAlO3/SrTiO3(001) heterojunction. Surf. Sci. Rep. 65, 317 (2010).

    CAS  Google Scholar 

  27. 27.

    M. Mayer: SIMNRA User’s Guide, Report IPP 9/113, Max-Planck-Institut fur Plasmaphysik (Garching, Germany, 1997).

    Google Scholar 

  28. 28.

    D.L. Young, H. Moutinho, Y. Yan, and T.J. Coutts: Growth and characterization of radio frequency magnetron sputter-deposited zinc stannate, Zn2SnO4, thin films. J. Appl. Phys. 92, 310 (2002).

    CAS  Google Scholar 

  29. 29.

    O. Kluth, C. Agashe, J. Hupkes, J. Muller, and B. Rech: Magnetron sputtered zinc stannate films for silicon thin film solar cells. In Proceedings of Third World Conference on Photovoltaic Energy Conversion; K. Kurokawa, L.L. Kazmerski, B. McNelis, M. Yamaguchi, C. Wronski, W.C. Sinke, eds., IEEE, Japan, 2003; p. 1800.

    Google Scholar 

  30. 30.

    H.A. Khorami, M. Keyanpour–Rad, and M.R. Vaezi: Synthesis of SnO2/ZnO composite nanofibers by electrospinning method and study of its ethanol sensing properties. Appl. Surf. Sci. 257, 7988 (2011).

    CAS  Google Scholar 

  31. 31.

    J.H. Ko, I.H. Kim, D. Kim, K.S. Lee, T.S. Lee, B. Cheong, and W.M. Kim: Transparent and conducting Zn-Sn-O thin films prepared by combinatorial approach. Appl. Surf. Sci. 253, 7398 (2007).

    CAS  Google Scholar 

  32. 32.

    M.A. Jin, H. Shulai, M.A. Honglei, and G.A.I Lingyun: Preparation and characterization of transparent conducting Zn-Sn-O films deposited on organic substrates at low temperature. Sci. China 46, 619 (2003).

    Google Scholar 

  33. 33.

    I. Stambolova, A. Toneva, V. Blaskov, D. Radev, Ya. Tsvetanova, S. Vassilev, and P. Peshev: Preparation of nanosized spinel stannate, Zn2SnO4, from a hydroxide precursor. J. Alloys Compd. 391, L1 (2005).

    CAS  Google Scholar 

  34. 34.

    Y. Yamada, Y. Seno, Y. Masuoka, and K. Yamashita: Nitrogen oxides sensing characteristics of Zn2SnO4 thin film. Sens. Actuators, B 49, 248 (1998).

    CAS  Google Scholar 

  35. 35.

    T. Ivetić, M.V. Nikolić, P.M. Nikolić, V. Blagojević, S. Đurić, T. Srećković, and M.M. Ristić: Investigation of zinc stannate synthesis using photoacoustic spectroscopy. Sci. Sintering 39, 153 (2007).

    Google Scholar 

  36. 36.

    T. Minami, S. Takata, H. Sato, and H. Sonohara: Properties of transparent zinc-stannate conducting films prepared by radio frequency magnetron sputtering. J. Vac. Sci. Technol., A 13, 1095 (1995).

    CAS  Google Scholar 

  37. 37.

    T. Minami, H. Sonohara, S. Takata, and H. Sato: Highly transparent and conductive zinc-stannate thin films prepared by RF magnetron sputtering. Jpn. J. Appl. Phys. 33, L1693 (1994).

    CAS  Google Scholar 

  38. 38.

    A. Oliziersky, P. Barquinha, A. Vilá, C. Magaña, E. Fortunato, J.R. Morante, and R. Martins: Role of Ga2O3-In2O3-ZnO channel composition on the electrical performance of thin-film transistors. Mater. Chem. Phys. 131, 512 (2011).

    Google Scholar 

  39. 39.

    A. Annamalai, Y.D. Eo, C. Im, and M.J. Lee: Surface and dye loading behavior of Zn2SnO4 nanoparticles hydrothermally synthesized using different mineralizers. Mater. Charact. 62, 1007 (2011).

    CAS  Google Scholar 

  40. 40.

    Freeware available at

  41. 41.

    G.S. Herman, Z. Dohnalek, N. Ruzycki, and U. Diebold: Experimental investigation of the interaction of water and methanol with anatase-TiO2(101). J. Phys. Chem. B 107, 2788 (2003).

    CAS  Google Scholar 

  42. 42.

    V.K. Jain, P. Kumar, M. Kumar, P. Jain, D. Bhandari, and Y.K. Vijay: Study of post annealing influence on structural, chemical and electrical properties of ZTO thin films. J. Alloys Compd. 509, 3541 (2011).

    CAS  Google Scholar 

  43. 43.

    S. Jeong, Y.G. Ha, J. Moon, A. Facchetti, and T. Marks: Role of gallium doping in dramatically lowering amorphous-oxide processing temperatures for solution-derived indium zinc oxide thin-film transistors. Adv. Mater. 22, 1346 (2010).

    CAS  Google Scholar 

  44. 44.

    L.J. Meng, C.P. Moreira de Sa, and M.P. dos Santos: Study of the structural properties of ZnO thin films by x-ray photoelectron spectroscopy. Appl. Surf. Sci. 78, 57 (1994).

    CAS  Google Scholar 

  45. 45.

    Y.F. Lu, H.Q. Ni, Z.H. Mai, and Z.M. Ren: The effects of thermal annealing on ZnO thin films grown by pulsed laser deposition. J. Appl. Phys. 88, 498 (2000).

    CAS  Google Scholar 

  46. 46.

    X.Y. Deng, A. Verdaguer, T. Herranz, C. Weis, H. Bluhm, and M. Salmeron: Surface chemistry of Cu in the presence of CO2 and H2O. Langmuir 24, 9474 (2008).

    CAS  Google Scholar 

  47. 47.

    K. Nomura, T. Kamiya, H. Ohta, M. Hirano, and H. Hosono: Defect passivation and homogenization of amorphous oxide thin-film transistor by wet O2 annealing. Appl. Phys. Lett. 93, 192107 (2008).

    Google Scholar 

  48. 48.

    M.G. Kim, M.G. Kanatzidis, A. Facchetti, and T.J. Marks: Low-temperature fabrication of high-performance metal oxide thin-film electronics via combustion processing. Nat. Mater. 10, 382 (2011).

    CAS  Google Scholar 

  49. 49.

    M. Fakhri, P. Görrn, T. Weimann, P. Hinze, and T. Riedl: Enhanced stability against bias-stress of metal-oxide thin film transistors deposited at elevated temperatures. Appl. Phys. Lett. 99, 123503 (2011).

    Google Scholar 

  50. 50.

    W.S. Choi: Interfacial study of metal oxide with source-drain electrodes and oxide semiconductors by XPS. Electron. Mater. Lett. 8, 87 (2012).

    CAS  Google Scholar 

  51. 51.

    Y. Xie, X. Zhao, Y. Chen, Q. Zhao, and Q. Yuan: Preparation and characterization of porous C-modified anatase titania films with visible light catalytic activity. J. Solid State Chem. 180, 3546 (2007).

    Google Scholar 

  52. 52.

    R.L. Hoffman: ZnO-channel thin-film transistors: Channel mobility. J. Appl. Phys. 95, 5813 (2004).

    CAS  Google Scholar 

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This research was performed in part using facilities at the Microproducts Breakthrough Institute and the Materials Synthesis and Characterization Facility at Oregon State University and at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research located at Pacific Northwest National Laboratory (PNNL). J.S.R. thanks PNNL for providing an Alternate Sponsored Fellowship during a portion of these studies. The project was funded by the Oregon Nanoscience and Microtechnologies Institute and the Office of Naval Research under contract number 200CAR262.

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Rajachidambaram, J.S., Sanghavi, S., Nachimuthu, P. et al. Characterization of amorphous zinc tin oxide semiconductors. Journal of Materials Research 27, 2309–2317 (2012).

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