Browsing by Author "Chen, Wei-Tsung"

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Amorphous indium-gallium-zinc-oxide visible-light phototransistor with a polymeric light absorption layer
(2010-11-15)
Zan, Hsiao-Wen
;
Chen, Wei-Tsung
;
Hsueh, Hsiu-Wen
;
Kao, Shih-Chin
;
Ku, Ming-Che
This work demonstrates a real-time visible-light phototransistor comprised of a wide-band-gap amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) and a narrow-band-gap polymeric capping layer. The capping layer and the IGZO layer form a p-n junction diode. The p-n junction absorbs visible light and consequently injects electrons into the IGZO layer, which in turn affects the body voltage as well as the threshold voltage of a-IGZO TFT. The hysteresis behavior due to the charges at IGZO back interface is also discussed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3517506]
Amorphous indium-gallium-zinc-oxide visible-light phototransistor with a polymeric light absorption layer
(2010-11-15)
Zan, Hsiao-Wen
;
Chen, Wei-Tsung
;
Hsueh, Hsiu-Wen
;
Kao, Shih-Chin
;
Ku, Ming-Che
This work demonstrates a real-time visible-light phototransistor comprised of a wide-band-gap amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) and a narrow-band-gap polymeric capping layer. The capping layer and the IGZO layer form a p-n junction diode. The p-n junction absorbs visible light and consequently injects electrons into the IGZO layer, which in turn affects the body voltage as well as the threshold voltage of a-IGZO TFT. The hysteresis behavior due to the charges at IGZO back interface is also discussed. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3517506]
Dual gate indium-gallium-zinc-oxide thin film transistor with an unisolated floating metal gate for threshold voltage modulation and mobility enhancement
(2011-04-11)
Zan, Hsiao-Wen
;
Chen, Wei-Tsung
;
Yeh, Chung-Cheng
;
Hsueh, Hsiu-Wen
;
Tsai, Chuang-Chuang
In this study, we propose a floating dual gate (FDG) indium-gallium-zinc-oxide (IGZO) thin film transistor (TFT) with a floating metal back gate that is directly contact with IGZO without a dielectric layer. The floating back gate effect is investigated by changing the work function (phi) of the back gate. The FDG IGZO TFT exhibits an improved field-effect mobility (mu), unchanged subthreshold swing (SS), high on/off current ratio, and a tunable threshold voltage ranged (V(th)) from -5.0 to + 7.9 V without an additional back gate power supply. (C) 2011 American Institute of Physics. [doi:10.1063/1.3578403]
High-Performance Light-Erasable Memory and Real-Time Ultraviolet Detector Based on Unannealed Indium-Gallium-Zinc-Oxide Thin-Film Transistor
(2012-01-01)
Chen, Wei-Tsung
;
Zan, Hsiao-Wen
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光電工程學系
;
顯示科技研究所
;
Department of Photonics
A light-erasable memory and a real-time ultraviolet (UV) detector were developed from an amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistor fabricated at room temperature without post-annealing. The natural defects within the IGZO or at the dielectric interface serve as electron traps to support a writing operation (switching down the channel conductance). A negative gate bias accompanied by UV illumination performs an erasing operation (switching up the channel conductance). After the writing/erasing of the proposed memory, an on/off ratio greater than 10(4) was maintained for a testing duration of 10 000 s. A real-time UV detector was also developed, and a light/dark ratio of roughly 10(4) was demonstrated.
Investigating electron depletion effect in amorphous indium-gallium-zinc-oxide thin-film transistor with a floating capping metal by technology computer-aided design simulation and leakage reduction
(2014-06-01)
Lu, Ting-Chou
;
Chen, Wei-Tsung
;
Zan, Hsiao-Wen
;
Ker, Ming-Dou
;
電機學院
The electron distribution in an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) with a floating metal-semiconductor (MS) back interface is analyzed using a technology computer-aided design (TCAD) model. The channel geometry (i.e., length and thickness) effect is carefully investigated. At a high work function (i.e., 5 eV) of the capping metal, electrons inside a-IGZO are mostly removed by the capping metal (electron depletion effect). The depletion of the IGZO film leads to an increase in threshold voltage in a-IGZO TFT. TCAD simulation reveals that increasing channel length and decreasing IGZO thickness significantly enhance such an electron depletion effect. Finally, the electron depletion effect is applied to a-IGZO TFT with a high-conductivity IGZO film to greatly suppress the leakage current by over 5 orders. (C) 2014 The Japan Society of Applied Physics
Light-Enhanced Bias Stress Effect on Amorphous In-Ga-Zn-O Thin-film Transistor with Lights of Varying Colors
(2011)
Chen, Wei-Tsung
;
Hsueh, Hsiu-Wen
;
Zan, Hsiao-Wen
;
Tsai, Chuang-Chuang
;
光電工程學系
This study investigates the light-color-dependent bias stress effect on an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT). The color of incident photons with energies lower than the optical band gap of IGZO (3.2 eV) was varied from blue to infrared. Regardless of the bias polarity, light is regarded as a promoter for bias-stress-induced instability. The light response of the a-IGZO TFT is both color-and bias-polarity-dependent. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3584088] All rights reserved.
Low Temperature Annealing with Solid-State Laser or UV Lamp Irradiation on Amorphous IGZO Thin-Film Transistors
(2010)
Zan, Hsiao-Wen
;
Chen, Wei-Tsung
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Chou, Cheng-Wei
;
Tsai, Chuang-Chuang
;
Huang, Ching-Neng
Instead of the conventional furnace annealing process with a temperature higher than 300 degrees C, two low temperature annealing methods are successfully demonstrated to suppress the instability problem of amorphous indium gallium zinc oxide (IGZO) thin film transistors (TFTs). With adequate Nd:yttrium aluminum garnet laser (266 nm) annealing energy density or Xe excimer UV lamp (172 nm) irradiation time, the on voltage shift is greatly suppressed from over 10 to 0.1 V. The influence of laser energy density and UV lamp irradiation time on the performance of IGZO TFTs is also investigated and explained. The proposed methods are promising for the development of amorphous IGZO TFTs on flexible substrates.
Methane Exposure on the Aluminum Nitride Gate Dielectric in Pentacene-Based Organic Thin-Film Transistors
(2009)
Chou, Cheng-Wei
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Zan, Hsiao-Wen
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Wang, Chung-Hwa
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Chen, Wei-Tsung
;
Tsai, Li-Shiuan
The device performance of a pentacene-based organic thin-film transistor (OTFT) fabricated on an aluminum nitride (AlN) surface can be improved by exposing AlN to a methane (CH(4)) gas before device fabrication. The mobility of the OTFT was enhanced from 0.046 to 0.924 cm(2)/V s by exposing AlN to CH(4). Its threshold voltage was reduced from -4.5 to -1.9 V. After the CH(4) exposure, the reduced surface energy of AlN was correlated with the improvement of the OTFT performance. The reduction of surface energy was correlated with the replacement of O-C=O bonds by C-O bonds and hydrocarbon (CH(x)) on the AlN surface. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3182823] All rights reserved.
Oxygen-Dependent Instability and Annealing/Passivation Effects in Amorphous In-Ga-ZnO Thin-Film Transistors
(2011-11-01)
Chen, Wei-Tsung
;
Lo, Shih-Yi
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Kao, Shih-Chin
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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.
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.