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Active and Passive Electronic Components
Volume 2013, Article ID 525017, 7 pages
Research Article

Logic Gates and Ring Oscillators Based on Ambipolar Nanocrystalline-Silicon TFTs

1Department of Electrical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
2Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
3School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

Received 2 August 2012; Revised 12 March 2013; Accepted 4 April 2013

Academic Editor: Olga Korostynsk

Copyright © 2013 Anand Subramaniam et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Nanocrystalline silicon (nc-Si) thin film transistors (TFTs) are well suited for circuit applications that require moderate device performance and low-temperature CMOS-compatible processing below 250°C. Basic logic gate circuits fabricated using ambipolar nc-Si TFTs alone are presented and shown to operate with correct outputs at frequencies of up to 100 kHz. Ring oscillators consisting of nc-Si TFT-based inverters are also shown to operate at above 20 kHz with a supply voltage of 5 V, corresponding to a propagation delay of <10 μs/stage. These are the fastest circuits formed out of nanocrystalline silicon TFTs to date. The effect of bias stress degradation of TFTs on oscillation frequency is also explored, and relatively stable operation is shown with supply voltages >5 V for several hours.