Browsing by Author "Chan, Po-Chun"

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Drain Current Response to Fast Illumination Pulse for Amorphous In-Ga-Zn-O Thin-Film Transistors
(2016-12)
Tai, Ya-Hsiang
;
Chang, Chun-Yi
;
Chan, Po-Chun
;
Dai, Jhih-Jie
;
交大名義發表
In this paper, the characteristic of the amorphous indium-gallium-zinc-oxide thin-film transistors under steady bias and fast multiple-pulse illumination stress is analyzed. The change in the drain current (Delta I-D) with respect to time is measured under different light intensities and pulse frequencies. The mechanism is proposed to explain the results by correlating the oxygen vacancy (V-O) reacting with the light-induced electron-hole (e-h) pairs. The results can be well analyzed by the fitting formula and parameters for the different light pulse frequencies. The tendency proves that not all the V-O react with e-h pairs at the same reaction rate. It is observed for the first time the number of V-O with fast reaction decreases with the pulse frequency. A model is proposed to describe the relation between the number and reaction rate of V-O.
Negative threshold voltage shift for LTPS TFTs under x-ray irradiation and gate bias
(2019-09-01)
Tai, Ya-Hsiang
;
Yeh, Shan
;
Chan, Po-Chun
;
Li, Yi-Shen
;
Huang, Shih-Hsuan
In this paper, the behavior of the low-temperature polycrystalline-silicon (LTPS) thin film transistors (TFTs) during x-ray irradiation and gate bias voltage (V-G) simultaneously is analyzed. Both n-type and p-type LTPS TFTs show negative shifts of threshold voltage under same dose of x-ray irradiation, regardless of the V-G polarity, while the field effect mobility of n-type LTPS TFT keeps fairly well. The degradation of subthreshold swing is attributed to the interface states, which can be repaired by 300 degrees C annealing. A model is proposed to explain the results for different V-G, and verified by changing the thickness of the gate oxide. More irradiation-induced holes are trapped by the far defects owing to the electric field. This study can be helpful to develop more stable devices or circuits for the application of x-ray image sensors.
The Vacancy Pool Model for Amorphous In-Ga-Zn-O Thin-Film Transistors
(2019-01-01)
Tai, Ya-Hsiang
;
Liu, Han-Wen
;
Chan, Po-Chun
;
光電工程學系
;
Department of Photonics
In this paper, the reaction rate of oxygen vacancy (VO) by the derivatives of threshold voltage (Vth) in the amorphous indium-gallium-zinc oxide thin-film transistors under light pulses with altering duty ratios is investigated. More importantly, after collecting and analyzing a lot of experimental results, a comprehensive model named VO pool is proposed. The proposed model can more universally describe the characteristic of VO reacting to the light and its degradation behavior under various kinds of stress condition.