Browsing by Author "Chang, Hsi-Ming"

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Effect of mechanical-strain-induced defect generation on the performance of flexible amorphous In-Ga-Zn-O thin-film transistors
(2016-12)
Liao, Po-Yung
;
Chang, Ting-Chang
;
Su, Wan-Ching
;
Chen, Yu-Jia
;
Chen, Bo-Wei
In this study, we investigate the effect of mechanical strain on the performance of flexible amorphous In-Ga-Zn-O (a-.InGaZnO) thin-film transistors. Drain current-gate voltage (ID-VG) and capacitance-voltage (C-V) transfer curves are measured to analyze the degradation behavior. The ID-VG characteristic exhibits a clear negative shift under mechanical strain regardless of the tension or compression state. In addition, the C-V characteristic curves show a leftward shift with extra distortion or stretching out under mechanical strain. This indicates that InGaZnO generates additional defects under this mechanical strain, a phenomenon that can be attributed to the generation of mechanical-strain-induced oxygen vacancies on the flexible a-InGaZnO TFTs. (C) 2016 The Japan Society of Applied Physics.
Impact of repeated uniaxial mechanical strain on flexible a-IGZO thin film transistors with symmetric and asymmetric structures
(2017-06-26)
Liao, Po-Yung
;
Chang, Ting-Chang
;
Su, Wan-Ching
;
Chen, Bo-Wei
;
Chen, Li-Hui
This letter investigates repeated uniaxial mechanical stress-induced degradation behavior in flexible amorphous In-Ga-Zn-O thin-film transistors (TFTs) of different geometric structures. Two types of via-contact structure TFTs are investigated: symmetrical and UI structure (TFTs with Iand U-shaped asymmetric electrodes). After repeated mechanical stress, I-V curves for the symmetrical structure show a significant negative threshold voltage (VT) shift, due to mechanical stress-induced oxygen vacancy generation. However, degradation in the UI structure TFTs after stress is a negative VT shift along with the parasitic transistor characteristic in the forward-operation mode, with this hump not evident in the reverse-operation mode. This asymmetrical degradation is clarified by the mechanical strain simulation of the UI TFTs. Published by AIP Publishing.
The effect of asymmetrical electrode form after negative bias illuminated stress in amorphous IGZO thin film transistors
(2017-03-06)
Su, Wan-Ching
;
Chang, Ting-Chang
;
Liao, Po-Yung
;
Chen, Yu-Jia
;
Chen, Bo-Wei
This paper investigates the degradation behavior of InGaZnO thin film transistors (TFTs) under negative bias illumination stress (NBIS). TFT devices with two different source and drain layouts were exanimated: one having a parallel format electrode and the other with UI format electrode. UI means that source/drain electrodes shapes is defined as a forked-shaped structure. The I-V curve of the parallel electrode exhibited a symmetric degradation under forward and reverse sweeping in the saturation region after 1000 s NBIS. In contrast, the I-V curve of the UI electrode structure under similar conditions was asymmetric. The UI electrode structure also shows a stretch-out phenomenon in its C-V measurement. Finally, this work utilizes the ISE-Technology Computer Aided Design (ISE-TCAD) system simulations, which simulate the electron field and IV curves, to analyze the mechanisms dominating the parallel and UI device degradation behaviors. Published by AIP Publishing.
The effect of asymmetrical electrode form after negative bias illuminated stress in amorphous IGZO thin film transistors (vol 110, 103502, 2017)
(2017-04-10)
Su, Wan-Ching
;
Chang, Ting-Chang
;
Liao, Po-Yung
;
Chen, Yu-Jia
;
Chen, Bo-Wei
The effect of device electrode geometry on performance after hot-carrier stress in amorphous In-Ga-Zn-O thin film transistors with different via-contact structures
(2017-05-15)
Liao, Po-Yung
;
Chang, Ting-Chang
;
Chen, Yu-Jia
;
Su, Wan-Ching
;
Chen, Bo-Wei
In this letter, the effects of hot carriers on amorphous In-Ga-Zn-O thin film transistors (TFTs) of different geometric structures were investigated. Three types of via-contact structure TFTs are used in this experiment, defined as source-drain large (SD large), source-drain normal (SD normal), and fork-shaped. After hot-carrier stress, the I-V curves of both SD normal and fork-shaped TFTs with U-shaped drains show a threshold voltage shift along with the parasitic transistor characteristic in the reverse-operation mode. Asymmetrical degradation is exhibited in an ISE-TCAD simulation of the electric field, which shows the distribution of hot electrons injected into the etch-stop layer below the redundant drain electrode. Published by AIP Publishing.