College of Engineering  |  Department of Electrical Engineering and Computer Science  |  ECE Division

Contact Information:
Prof. J. Kanicki
University of Michigan
EECS Department
2307 EECS Bldg.
1301 Beal Ave
Ann Arbor, MI 48109-2122

Tel: (734) 936-0964 (Office)
Tel: (734) 936-0972 (Lab)
Fax: (734) 615-2843

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Electrical Stability of Hexagonal a-Si:H TFTs

Geonwook Yoo, Hojin Lee and Jerzy Kanicki

Amorphous silicon thin-film transistors (a-Si:H TFTs) have been extensively used as pixel circuits for large-area flat-panel displays and X-ray imagers due to excellent spatial uniformity and low fabrication cost. To use such devices for various analog amplifiers, switches, and AM-OLEDs, a higher drain current and better electrical stability under prolonged bias stress are required.

In this project, we assess the potential of hexagonal (HEX-) TFTs connected in parallel for aforementioned applications by evaluating their electrical stability. We measured threshold voltage shift (ΔVth) induced by current temperature stress of single HEX-TFTs at an elevated temperature (80 °C) and then investigated their contribution to overall ΔVth of multiple HEX-TFTs. The multiple HEX-TFTs show a better electrical stability compared to standard TFT for similar W/L ratio. It is found that one specific HEX unit in the multiple HEX-TFTs does not dominate or/and affect the overall HEX-TFTs electrical instability. These new hexagonal devices show promising electrical characteristics for AM-OLEDs and other flat panel displays. This research was partially supported by LG Display, Korea.

G. Yoo, et al., IEEE EDL, 31, (2010) 53.
H. Lee et al., J. Appl. Phys., 105(2009) 124522


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