Abstract

In this paper, we propose a new amorphous silicon (a-Si:H) thin-film transistor (TFT) pixel circuit employing negative bias annealing for active-matrix organic light-emitting diode (AMOLED). This circuit consists of two driving TFTs, four switching TFTs, and two storage capacitors. The new driving scheme adopting negative bias annealing entitled polarity balanced driving (PBD) successfully suppresses the troublesome V<sub>th</sub> shift in a-Si:H TFT. The proposed pixel circuit was verified by simulation and fabrication. When a severe electrical bias is applied more than 24 hours and a temperature is increased up to 60 °C rather than a room temperature, the current stability (I<sub>after_sttress</sub>/I<sub>max</sub>) of the proposed PBD pixel is 0.97 while that of the conventional one is 0.72. Our experimental results show that the proposed PBD can improve a stability of a-Si:H TFT because the applied negative gate bias can successfully suppress V<sub>th</sub> shift of the current-driving a-Si:H TFT.

© 2007 IEEE

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  1. J. L. Sanford, F. R. Libsch, "TFT AMOLED pixel circuits and driving methods," SID'03 Dig. (2003) pp. 10-13.
  2. J. C. Goh, J. Jang, K. S. Cho, C. K. Kim, "A new a-Si:H thin-film transistor pixel circuit for active-matrix organic light-emitting diodes," IEEE Electron Device Lett. 24, (2003).
  3. K. Shimizu, O. Sugiura, M. Matsumura, "High-mobility Poly-Si thin-film transistors fabricated by a novel eximer laser crystallization method," IEEE Trans. Electron Devices 40, (1993).
  4. R. M. A. Dawson, Z. Shen, D. A. Furst, S. Conner, J. Hsu, M. G. Kane, R. G. Stewart, A. Ipri, C. N. King, P. J. Green, R. T. Flegal, S. Pearson, W. A. Barrow, E. Dickey, K. Ping, S. Robbinson, "The impact of the transient response of organic light emitting diodes on the design of active matrix OLED displays," Proc. IEEE IEDM (1998) pp. 875-878.
  5. J. H. Lee, W. J. Nam, S. H. Jung, M. K. Han, "A new current scaling pixel circuit for AMOLED," IEEE Electron Device Lett. 25, 280-282 (2004).
  6. T. Hasumi, S. Takasugi, K. Kanoh, Y. Kobayashi, "New OLED pixel circuit and driving method to suppress threshold voltage shift of a-Si:H TFT," SID'06 Dig. (2006) pp. 1547-1550.
  7. A. Nathan, S. Alexander, R. Huang, D. Sriakhilev, C. Church, P. Arsenault, S. Ashitiani, R. Chaji, "a-Si for AMOLED-meeting the performance and cost demands of display application (cell phone to HDTV)," SID'06 Dig. (2006) pp. 1543-1546.
  8. M. K. Han, J. H. Lee, W. J. Nam, "Thin film transistor (TFT) pixel design for AMOLED," IMID/IDMC '06 Dig. (2006).
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  10. M. J. Powell, C. V. Berkel, A. R. Franklin, S. C. Deane, W. I. Milne, "Defect pool in amorphous-silicon thin-film transistors," Phys. Rev. B 45, 4160-4170 (1992).
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  13. D. A. Fellows, M. V. Wood, O. Prache, S. Jones, "AMOLED (active matrix OLED) functionality and usable lifetime at temperature," Proc. SPIE (2005) pp. 138-149.
  14. K. Sakariya, C. K. M. Ng, P. Servati, A. Nathan, "Accelerated stress testing of a-Si:H TFT pixel circuits for AMOLED display," IEEE Trans. Electron Devices 52, no. 12, Dec 2005.

Appl. Phys. Lett. (1)

M. J. Powell, "Charge trapping instability in amorphous silicon-silicon nitride thin-film transistor," Appl. Phys. Lett. 43, 597-599 (1983).

Appl. Phys. Lett. (2)

C. V. Berkel, M. J. Powell, "Resolution of amorphous silicon thin-film transistor instability mechanisms using ambipolar transistors," Appl. Phys. Lett. 51, 1094-1096 (1987).

M. J. Powell, S. C. Deane, W. I. Milne, "Bias-stress-induced creation and removal of dangling-bond states in amorphous silicon thin-film transistors," Appl. Phys. Lett. 60, 207-209 (1992).

IEEE Electron Device Lett. (1)

J. C. Goh, J. Jang, K. S. Cho, C. K. Kim, "A new a-Si:H thin-film transistor pixel circuit for active-matrix organic light-emitting diodes," IEEE Electron Device Lett. 24, (2003).

IEEE Electron Device Lett. (1)

J. H. Lee, W. J. Nam, S. H. Jung, M. K. Han, "A new current scaling pixel circuit for AMOLED," IEEE Electron Device Lett. 25, 280-282 (2004).

IEEE Trans. Electron Devices (1)

K. Sakariya, C. K. M. Ng, P. Servati, A. Nathan, "Accelerated stress testing of a-Si:H TFT pixel circuits for AMOLED display," IEEE Trans. Electron Devices 52, no. 12, Dec 2005.

IEEE Trans. Electron Devices (1)

K. Shimizu, O. Sugiura, M. Matsumura, "High-mobility Poly-Si thin-film transistors fabricated by a novel eximer laser crystallization method," IEEE Trans. Electron Devices 40, (1993).

Phys. Rev. B (1)

M. J. Powell, C. V. Berkel, A. R. Franklin, S. C. Deane, W. I. Milne, "Defect pool in amorphous-silicon thin-film transistors," Phys. Rev. B 45, 4160-4170 (1992).

Other (6)

R. M. A. Dawson, Z. Shen, D. A. Furst, S. Conner, J. Hsu, M. G. Kane, R. G. Stewart, A. Ipri, C. N. King, P. J. Green, R. T. Flegal, S. Pearson, W. A. Barrow, E. Dickey, K. Ping, S. Robbinson, "The impact of the transient response of organic light emitting diodes on the design of active matrix OLED displays," Proc. IEEE IEDM (1998) pp. 875-878.

T. Hasumi, S. Takasugi, K. Kanoh, Y. Kobayashi, "New OLED pixel circuit and driving method to suppress threshold voltage shift of a-Si:H TFT," SID'06 Dig. (2006) pp. 1547-1550.

A. Nathan, S. Alexander, R. Huang, D. Sriakhilev, C. Church, P. Arsenault, S. Ashitiani, R. Chaji, "a-Si for AMOLED-meeting the performance and cost demands of display application (cell phone to HDTV)," SID'06 Dig. (2006) pp. 1543-1546.

M. K. Han, J. H. Lee, W. J. Nam, "Thin film transistor (TFT) pixel design for AMOLED," IMID/IDMC '06 Dig. (2006).

J. L. Sanford, F. R. Libsch, "TFT AMOLED pixel circuits and driving methods," SID'03 Dig. (2003) pp. 10-13.

D. A. Fellows, M. V. Wood, O. Prache, S. Jones, "AMOLED (active matrix OLED) functionality and usable lifetime at temperature," Proc. SPIE (2005) pp. 138-149.

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