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The Origin and Nature of Contact Resistance in a-Si:H TFTs

Published online by Cambridge University Press:  16 February 2011

Serag M. Gadelrab
Affiliation:
University of Waterloo, Department of Electrical and Computer Engineering, Waterloo, Ontario, Canada N2L 3G1.
Savvas G. Chamberlain
Affiliation:
University of Waterloo, Department of Electrical and Computer Engineering, Waterloo, Ontario, Canada N2L 3G1.
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Abstract

The origin of contact resistance in a-Si:H TFTs is investigated by formulating a model for the contact limited current. The Model accounts for the independent contributions of the Metal–n+a-Si:H interface resistance and the space charge limited conduction through the intrinsic a-Si:H film. Using our contact current model we investigated the I–V behavior of an n–i–n structure with a thin a-Si:H layer (=700Å) and found that the resistance of the Metal–n+a-Si:H interface is nonlinear. We incorporated the contact limited current expression into a full TFT Model and simulated the TFT performance for a wide range of Metal–n+a-Si:H interface resistance values and intrinsic a-Si:H film thicknesses. We found that the Metal–n+a-Si:H interface resistance dominates over space charge limited conduction for the thicknesses of intrinsic a-Si:H films used in AM-LCD switches. This trend is sustained even when the effective resistance of the Metal–n+a-Si:H interface decreases due to the nonlinear current conduction across it.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

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