Browsing by Author "Wu, Chang-Pei"

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Characterization of environment-dependent hysteresis in indium gallium zinc oxide thin film transistors
(2013-09-01)
Chen, Yu-Chun
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Chang, Ting-Chang
;
Li, Hung-Wei
;
Chung, Wan-Fang
;
Chen, Shih-Cheng
This study investigates environmentally dependent electrical performance as a function of hysteresis phenomena for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). Because ambient gas has a great influence on the electrical characteristics of zinc oxide-based TFTs during electrical measurements, the hysteresis for current-voltage and capacitance-voltage measurements are employed in different ambient gases (ambient air, vacuum, oxygen ambient and moisture ambient) to study this issue. Although the hysteresis phenomenon has been explained by the charge trapping and de-trapping model, in order to obtain stable electrical characteristics it is necessary to clarify the original principal mechanism leading to threshold voltage instability under gate bias operations in different environments. Also, the relationship between de-trapping rate and electrical hysteresis is investigated by prolonging the integration time of the semiconductor parameter analyzer. This study may be of importance in explaining the dynamic relationship between the TFT electrical characteristics and ambient gas, as well as providing a better understanding of the environment-dependent hysteresis phenomenon of the IGZO TFTs. (C) 2012 Elsevier B.V. All rights reserved.
High-stability oxygen sensor based on amorphous zinc tin oxide thin film transistor
(2012-06-25)
Chen, Yu-Chun
;
Chang, Ting-Chang
;
Li, Hung-Wei
;
Chung, Wan-Fang
;
Wu, Chang-Pei
This research presents a sol-gel derived zinc tin oxide thin film transistor (TFT) as a high-stability oxygen sensor. Due to its high sensitivity, oxygen has been traditionally regarded as having a negative influence on the electrical characteristics of zinc-based TFTs; however, TFTs can also act as an oxygen sensor. After illumination with visible light in oxygen-rich ambient, a significant increase in drain current of nearly 10 4 times occurs with fixed gate and drain voltages. It is expected that an optimized method of illumination can help to reset the electrical characteristics or distinguish the on/off state of this reliable oxygen sensor. (C) 2012 American Institute of Physics. [ http://dx.doi.org/10.1063/1.4731773]
The suppressed negative bias illumination-induced instability in In-Ga-Zn-O thin film transistors with fringe field structure
(2012-11-26)
Chen, Yu-Chun
;
Chang, Ting-Chang
;
Li, Hung-Wei
;
Hsieh, Tien-Yu
;
Chen, Te-Chih
This study investigates the suppressed negative gate bias illumination stress (NBIS) -induced instability of via-type amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) with fringe field (FF) structures. The less negative threshold voltage shifts of devices after NBIS are showed when device has larger FF structures. This finding is attributed to more dispersive distribution of photo-generated holes in the width direction of a-IGZO during NBIS, which reduce the hole trapping phenomenon in the front channel interface. The a-IGZO TFT with FF structure is expected to be an effective method to increase the electrical reliability of devices after NBIS. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767996]