Skip to main content

Effects of contact resistance on the evaluation of charge carrier mobilities and transport parameters in amorphous zinc tin oxide thin-film transistors


Accurate determination of the charge transport characteristics of amorphous metal-oxide transistors requires the mitigation of the effects of contact resistance. The use of additional electrodes as voltage probes can overcome contact resistance-related limitations and yields accurate charge carrier mobility values, trap depths and temperature and carrier density dependencies of mobility as well as trap depths. We show that large differences in measured charge carrier mobility values are obtained when such contact resistances are not factored out. Upon exclusion of the contact resistance, the true temperature dependence of charge carrier mobility appears in the form of two clearly distinct mobility regimes. Analyzing these revealed mobility regions leads to a more accurate determination of the underlying transport physics, which shows that contact resistance-related artefacts yield incorrect trends of trap depth with gate voltage, potentially leading to a misconstruction of the charge transport picture. Furthermore, a comparison of low- and high-mobility samples indicates that the observed effects are more general.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5


  1. K. Abe, N. Kaji, H. Kumomi, K. Nomura, T. Kamiya, M. Hirano, H. Hosono, IEEE Trans. Electron. Devices 58, 3463 (2011)

    Article  ADS  Google Scholar 

  2. H.Q. Chiang, J.F. Wager, R.L. Hoffman, J. Jeong, D.A. Keszler, APL 86, 013503 (2005)

    Google Scholar 

  3. V. Craciun, J. Elders, J.G.E. Gardeniers, I.W. Boyd, APL 65, 2963 (1994)

    Google Scholar 

  4. S. Dutta, A. Dodabalapur, Sens. Actuators B Chem. S34, 50 (2009)

    Article  Google Scholar 

  5. P.T. Erslev, E.S. Sundholm, R.E. Presley, D. Hong, J.F. Wager, J.D. Cohen, APL 95, 192115 (2009)

    Google Scholar 

  6. Y. Fu, Y.-M. Mu, M. Willander, Superlattices Microstruct. 23, 417 (1998)

    Article  ADS  Google Scholar 

  7. W. Hu, R.L. Peterson, J. Mat. Res. 27, 2286 (2012)

    Article  ADS  Google Scholar 

  8. W.B. Jackson, R.L. Hoffman, G.S. Herman, APL 87, 193503 (2005)

    Google Scholar 

  9. J. Jeong, J. Kim, G.J. Lee, B.-D. Choi, APL 100, 023506 (2012)

    Google Scholar 

  10. C.R. Kagan and Paul Andry, Thin-Film Transistors. CRC Press, 1st edition (2003)

  11. Y.-H. Kim, J.-S. Heo, T.-H. Kim, S. Park, M.-H. Yoon, J. Kim, M.S. Oh, G.-R. Yi, Y.-Y. Noh, S.K. Park, Nature 489, 128 (2012)

    Article  ADS  Google Scholar 

  12. P.G. Le Comber, W.E. Spear, PRL 25, 509 (1970)

    Article  ADS  Google Scholar 

  13. D.H. Lee, D.-H. Lee, Y.-J. Chang, G.S. Herman, C.-H. Chang, Adv. Mat. 19, 843 (2007)

    Article  Google Scholar 

  14. C.-G. Lee, A. Dodabalapur, APL 96, 243501 (2010)

    Google Scholar 

  15. C.-G. Lee, B. Cobb, A. Dodabalapur, APL 97, 203505 (2010)

    Google Scholar 

  16. C.-G. Lee, A. Dodabalapur, IEEE Electron. Device Lett. 31, 1410 (2010)

    Article  ADS  Google Scholar 

  17. W. Lim, J.H. Jang, S.-H. Kim, D.P. Norton, V. Craciun, S.J. Peartona, F. Ren, H. Chen, J. Vac. Sci. Technol. B 27, 126 (2009)

    Article  Google Scholar 

  18. S. Murali, J.S. Rajachidambaram, S.-Y. Han, C.-H. Chang, G.S. Herman, J.F. Conley Jr, Solid State Elec. 79, 248252 (2013)

    Article  Google Scholar 

  19. K. Nomura, A. Takagi, T. Kamiya, H. Ohta, M. Hirano, H. Hosono, JJAP 45, 4303 (2006)

    ADS  Google Scholar 

  20. B.N. Pal, B.M. Dhar, K.C. See, H.E. Katz, Nat. Mat. 8, 898 (2009)

    Article  Google Scholar 

  21. M.-K. Ryu, J.-B. Seon, I.S. Kee, Y. G. Lee, S.Y. Lee, Sid Symp. Digest Techn. Papers 40, no. 1 (2009)

  22. S.-J. Seo, C.G. Choi, Y.H. Hwang, B.-S. Bae, J. Phys. D Appl. Phys. 42, 035106 (2009)

    Article  ADS  Google Scholar 

  23. M. Shur, S. Rumyantsev, M. Levinshtein, SiC Materials and Devices, Vol. 2. Prentice Hall, 1st edition (1997)

Download references


Financial support of the Schweizerischer Nationalfonds (SNF) with the grant numbers PBFRP2-138632 and PBFRP2-142820 and of the Office of Naval Research with the grant number A002181202 is gratefully acknowledged.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Leander Schulz.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Schulz, L., Yun, EJ. & Dodabalapur, A. Effects of contact resistance on the evaluation of charge carrier mobilities and transport parameters in amorphous zinc tin oxide thin-film transistors. Appl. Phys. A 115, 1103–1107 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: