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High Electron Mobility (˜150 cm2/Vs) PECVD Nanocrystalline Silicon Top-Gate TFTs at 260 °C

Published online by Cambridge University Press:  01 February 2011

Czang-Ho Lee
Affiliation:
Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
Andrei Sazonov
Affiliation:
Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
Arokia Nathan
Affiliation:
Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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Abstract

Undoped nanocrystalline silicon (nc-Si:H) films were prepared by conventional 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) at 260 °C, using highly H2-diluted SiH4 plasma. The nc-Si:H films were evaluated using electrical, structural, and chemical measurements. The optimized nc-Si:H film showed an oxygen concentration (CO) of ˜1.5 X 1017 at./cm3 and a dark conductivity (σD) of ˜10-6 S/cm, while the Raman crystalline volume fraction (XC) was ˜85 %. Top-gate staggered TFTs with a ˜100 nm nc-Si:H channel layer and an amorphous silicon oxide (a-SiOx) as the gate dielectric were fabricated. The TFTs showed a field effect mobility (μFE) of ˜150 cm2/Vs, a threshold voltage (VT) of ˜2 V, a subthreshold slope (S) of ˜0.25 V/dec, and an ON/OFF current ratio more than 106. To the best of our knowledge, the TFT mobility reported here is the highest achieved to date using state-of-the-art nc-Si:H films prepared by direct PECVD.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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