Active Pixel TFT Arrays for Digital Fluoroscopy in a-Si:H Technology


Major development challenges in application of hydrogenated amorphous silicon (a-Si:H) technology to large area digital X-ray imaging and technological attributes such as low temperature deposition and high uniformity over large area evolve around dynamic imaging modalities such as fluoroscopy, which demands both high speed readout and signal amplification capabilities in addition to long term device stability. This work reports on initial results of a variety of TFT active pixel sensor (APS) structures in a-Si:H technology, each demonstrating unique capabilities such as enhancements in signal gain, TFT threshold voltage immunity, and real-time high speed readout.

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


  1. 1

    K.S. Karim, A. Nathan, J.A. Rowlands, “Amorphous silicon active pixel sensor readout circuit for digital imaging,” IEEE Trans. Elec. Dev., Vol. 50, 1, 200–208 (2003).

    Article  Google Scholar 

  2. 2

    A. Nathan Karim, J.A. Rowlands, “Active pixel sensor architectures in a-Si for medical imaging,” J. Vac. Sci. Technol. A, 20 (3), 1095–1099 (2002).

    CAS  Article  Google Scholar 

  3. 3

    M.J. Powell, “Charge trapping instabilities in amorphous silicon-silicon nitride thin-film transistors,” Appl. Phys. Lett., 43 (6), 15 (1983).

    Article  Google Scholar 

  4. 4

    M.J. Powell, C. van Berkel, I.D. French, D.H. Nicholls, “Bias dependence of instability mechanisms in amorphous silicon thin film transistors,” Appl. Phys. Lett., 51, 1242 (1987).

    CAS  Article  Google Scholar 

  5. 5

    M. Wany, G.P. Israel, “CMOS image sensor with NMOS-only global shutter and enhanced responsivity,” IEEE Trans. Elec. Dev., Vol. 50, 1, 57–62 (2003).

    Article  Google Scholar 

  6. 6

    K. Khakzar, E.H. L Leuder, ‘Modeling of amorphous silicon thin-film transistors for circuit simulations with SPICE’, IEEE Trans. Elec. Dev., 1992, 39, pp.1428–1434.

    Article  Google Scholar 

  7. 7

    P. Servati, A. Nathan,: ‘Modeling of the static and dynamic behavior of amorphous silicon thin-film transistors’, J. of Vac. Sci. Technol., 20, 1038–1042 (2002).

    CAS  Article  Google Scholar 

  8. 8

    Spectretm: Cadence design systems Inc.

Download references


This work is supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada.

Author information



Corresponding author

Correspondence to Jackson Lai.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lai, J., Safavian, N., Nathan, A. et al. Active Pixel TFT Arrays for Digital Fluoroscopy in a-Si:H Technology. MRS Online Proceedings Library 862, 224 (2004).

Download citation