Browsing by Author "Fang, Chun-Hsiang"

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Oxygen-Dependent Instability and Annealing/Passivation Effects in Amorphous In-Ga-ZnO Thin-Film Transistors
(2011-11-01)
Chen, Wei-Tsung
;
Lo, Shih-Yi
;
Kao, Shih-Chin
;
Zan, Hsiao-Wen
;
Tsai, Chuang-Chuang
This letter discusses the reason for the instability of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) under both positive and negative bias stresses. This instability is significantly influenced by the oxygen content in the bulk IGZO and the surrounding environment. The as-fabricated low-temperature devices can only endure a single polarized bias stress. An a-IGZO TFT that is stable toward both positive and negative bias stresses with large relaxation times of 95 x 10(4) and 371 x 10(4) s, respectively, is achieved by annealing and passivation.
Reliability improvement of InGaZnO thin film transistors encapsulated under nitrogen ambient
(2012-04-09)
Wu, Chun-Yu
;
Cheng, Huang-Chung
;
Wang, Chao-Lung
;
Liao, Ta-Chuan
;
Chiu, Po-Chun
The nitrogen ambient encapsulation (NAE) technique is introduced to improve the reliability issue for the amorphous InGaZnO (a-IGZO) thin-film transistors under positive gate bias stress (PGBS). For the NAE devices, the threshold voltage (Vth) shift is significantly decreased from 1.88 to 0.09 V and the reduction of saturation drain current is improved from 15.75 to 5.61 mu A as compared to the bare a-IGZO counterparts after PGBS. These improvements are attributed to the suppression of negatively charged oxygen adsorption on the a-IGZO backsurface and thereby well maintain the channel potential of NAE devices, which in turn sustain the Vth during PGBS. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3702794]
Study on Oxygen-dependent Instability of Amorphous In-Ga-Zn-O TFT and Completely Stable Device under Both Positive and Negative Bias Stresses
(2010)
Chen, Wei-Tsung
;
Zan, Hsiao-Wen
;
Lo, Shih-Yi
;
Kao, Shih-Chin
;
Tsai, Chuang-Chuang
A complete experiment is conducted to verify the origin of stress-induced instability in an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT). It is found that the oxygen ratio in an IGZO layer strongly influences the device stability under bias stress. For realizing an adequately stable device, post-annealing and passivation are performed in order.