Thin-Film Phototransistor with nc-Si:H/a-Si:H Bilayer Channel

Abstract

There is significant interest in optical sensors whose fabrication process is fully compatible with existing flat panel display thin film transistor (TFT) technology. Here, we report a field-effect phototransistor with a channel comprising a thin nanocrystalline silicon (nc-Si:H) transport layer and a thicker hydrogenated amorphous silicon (a-Si:H) absorption layer. The implementation of nc-Si:H layer improves device stability in comparison with a-Si:H phototransistors, resulting in reduced threshold voltage shift. Semiconductor and dielectric layers were deposited by radio-frequency plasma enhanced chemical vapor deposition at 280°C. The device characterization included the dark and light transfer characteristics, spectral-response and dynamic measurements. The external quantum efficiency was measured as a function of incident photon flux at different biasing conditions. The phototransistor with channel length of 24 microns and photosensitive area of 1.4 mm2 shows an off-current of about 1 pA, and photo-conductive gain up to 200 at low incident intensities. Thus, the results demonstrate the feasibility of the phototransistor for low light level detection.

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References

  1. 1.

    S. GadelRab, S. Chamberlain, IEEE Trans. Electron Devices 45, 465 (1998).

    CAS  Article  Google Scholar 

  2. 2.

    S. H. Kim, E. B. Kim, H. Y. Choi, M. H. Kang, J. H. Hur, J. Jang, Solid-State Electronics 52, 478 (2008).

    CAS  Article  Google Scholar 

  3. 3.

    N. Papadopoulos, D. Papakostas, and A. Hatzopoulos, J. Display. Technol. 6, 150 (2010).

    Article  Google Scholar 

  4. 4.

    Y. Kaneko, N. Koike, K. Tsutsui, and T. Tsukada, Appl. Phys. Lett. 56, 650 (1990).

    CAS  Article  Google Scholar 

  5. 5.

    S. M. GadelRab and S. G. Chamberlain, IEEE Trans. Electron Devices 44, 1789 (1997).

    CAS  Article  Google Scholar 

  6. 6.

    S. M. GadelRab and S. G. Chamberlain, IEEE Trans. Electron Devices 45, 465 (1998).

    CAS  Article  Google Scholar 

  7. 7.

    C.-H. Lee, A. Sazonov, A. Nathan, J. Robertson, Appl. Phys. Lett. 89, 252101 (2006).

    Article  Google Scholar 

  8. 8.

    M. R. Esmaeili-Rad, A. Sazonov, A. G. Kazanskii. A. A. Khomich. A. Nathan, J. Mater. Sci: Mater. Electron. 18, S405 (2007).

    CAS  Google Scholar 

  9. 9.

    M. R. Esmaeili-Rad, A. Sazonov, A. Nathan, J. Appl. Phys. 103, 074502 (2008).

    Article  Google Scholar 

  10. 10.

    A. Sazonov, D. Striakhilev, C.-H. Lee, and A. Nathan, Proc. IEEE 93, 1420 (2005).

    CAS  Article  Google Scholar 

  11. 11.

    A. Nathan, A. Kumar, K. Sakariya, P. Servati, K. S. Karim, D. Striakhilev, and A. Sazonov, IEEE J. Sel. Top. Quant. Electron. 10, (2004) 58.

    CAS  Article  Google Scholar 

  12. 12.

    Thin-film transistors, edited by C. R. Kagan and P. Andry (Marcel Dekker, Inc., New York, 2003).

    Google Scholar 

  13. 13.

    M. R. Esmaeili-Rad, A. Sazonov, A. Nathan, Appl. Phys. Lett. 91, 113511 (2007).

    Article  Google Scholar 

  14. 14.

    Technology and Applications of Amorphous Silicon, edited by R. A. Street (Springer, Berlin, 2000).

    Google Scholar 

Download references

Acknowledgments

The authors are grateful to the Portuguese Foundation of Science and Technology for financial support of this research through the PIDDAC Program funds and research Project PTDC/EEA-ELC/115577/2009, and to the Giga-to-Nanoelectronics Centre at the University of Waterloo for providing the necessary equipment and technical help to carry out this work.

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Correspondence to Y. Vygranenko.

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Vygranenko, Y., Sazonov, A., Fernandes, M. et al. Thin-Film Phototransistor with nc-Si:H/a-Si:H Bilayer Channel. MRS Online Proceedings Library 1426, 205–210 (2012). https://doi.org/10.1557/opl.2012.1180

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