Browsing by Author "Teng, Li-Feng"

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Ambient Stability Enhancement of Thin-Film Transistor With InGaZnO Capped With InGaZnO:N Bilayer Stack Channel Layers
(2011-10-01)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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Li, Fu-Hai
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Fuh, Chur-Shyang
A thin-film transistor (TFT) with bilayer stack structure of amorphous nitrogenated InGaZnO (IGZO) (a-IGZO:N) on an IGZO channel is proposed to enhance device stability. The a-IGZO: N acting as a back-channel passivation (BCP) is formed sequentially just after the sputter-deposited amorphous IGZO (a-IGZO) film with in situ nitrogen incorporation process. The a-IGZO:N can effectively prevent the a-IGZO channel from exposing to the atmosphere and retarding interactions with ambient oxygen species. Also, the optical energy bandgap of the a-IGZO:N film is decreased due to the addition of nitrogen. This causes the a-IGZO TFT with a-IGZO:N BCP to exhibit high immunity to the ultraviolet-radiation impact.
Bipolar resistive switching characteristics of Al-doped zinc tin oxide for nonvolatile memory applications
(1970-01-01)
Fan, Yang-Shun
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Liu, Po-Tsun
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Teng, Li-Feng
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Hsu, Ching-Hui
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光電工程學系
"Resistive random access memory using Al-doped zinc tin oxide (AZTO) as resistive switching layer was prepared by radio-frequency magnetron sputtering at room temperature. The Ti/AZTO/Pt device exhibits reversible and robust bi-stable resistance switching behavior over hundreds of switching cycles within 2 V sweep voltage. The Ti/AZTO/Pt device showed stable retention characteristics for over 104 s under read disturb stress condition. Besides, the electrical conduction mechanism was dominated by ohmic conduction in low resistance state, while the current transport behavior followed a trap-controlled space-charge-limited conduction process in high resistance state. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742737]"
Characteristics imrovement for flexible a-Si:H Thin Film Transistor with post treatment processes
(2010)
Teng, Li-Feng
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Liu, Po-Tsun
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Chou, Yi-Teh
;
Fan, Yang-Shun
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光電工程學系
The performances of flexible a-Si:H TFTs on stainless foil with and without silicon nitride passivation layer were discussed in this study. The experiment results indicated the reliability of a-Si:H TFTs with passivation layer under mechanical strains was improved. That\'s related to the hydrogen passivating effect during deposition and post-annealing process.
Charge pumping method for photosensor application by using amorphous indium-zinc oxide thin film transistors
(2009-06-15)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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光電工程學系
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顯示科技研究所
The study investigated the photoreaction behavior of amorphous indium-zinc oxide thin film transistor (a-IZO TFT), which was thought to be insensitive to visible light. The obvious threshold voltage shift was observed after light illumination, and it exhibited slow recovery while returning to initial status. The photoreaction mechanism is well explained by the dynamic equilibrium of charge exchange reaction between O(2(g)) and O(2) in a-IZO layer. A charge pumping technique is used to confirm the mechanism and accelerate recoverability. Using knowledge of photoreaction behavior, an operation scheme of photosensing elements consist of a-IZO TFT is also demonstrated in this work.
Effects of microwave annealing on electrical enhancement of amorphous oxide semiconductor thin film transistor
(2012-09-24)
Teng, Li-Feng
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Liu, Po-Tsun
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Lo, Yuan-Jou
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Lee, Yao-Jen
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光電學院
By using microwave annealing technology instead of thermal furnace annealing, this work elucidates the electrical characteristics of amorphous InGaZnO thin film transistor (a-IGZO TFT) with a carrier mobility of 13.5 cm(2)/Vs, threshold voltage of 3.28 V, and subthreshold swing of 0.43 V/decade. This TFT performance with microwave annealing of 100 s is well competitive with its counterpart with furnace annealing at 450 degrees C for 1 h. A physical mechanism for the electrical improvement is also deduced. Owing to its low thermal budget and selective heating to materials of interest, microwave annealing is highly promising for amorphous oxide in semiconductor TFT manufacturing. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754627]
Effects of Microwave Annealing on Nitrogenated Amorphous In-Ga-Zn-O Thin-Film Transistor for Low Thermal Budget Process Application
(2013-09-01)
Fuh, Chur-Shyang
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Liu, Po-Tsun
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Teng, Li-Feng
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Huang, Sih-Wei
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Lee, Yao-Jen
In this letter, microwave annealing technology is proposed to reduce thermal budget for the manufacture of transparent conductive oxide thin-film transistor (TFT). With microwave annealing, a nitrogenated amorphous In-Ga-Zn-O (a-IGZO:N) TFT fabricated on glass panel behaves as a carrier mobility of 4.21 cm(2)/V s and threshold voltage of 2.91 V. The performance of microwave-treated a-IGZO: N TFT with annealing process duration of 300 s is well competitive with its counterpart treated by thermal furnace annealing at 350 C for 1 h. Owing to its low thermal budget and selective heating to materials of interest, the microwave annealing has great potential for flexible oxide TFT applications.
Electrical performance and photo-responses enhancement by in situ nitrogen incorporation to amorphous InGaZnO thin-film transistors
(2011)
Teng, Li-Feng
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Liu, Po-Tsun
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Fuh, Chur-Shyang
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Chou, Yi-Teh
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Li, Fu-Hai
We studied wavelength dependent photo-responses in amorphous nitrogenated InGaZnO thin-film transistors (a-IGZO:N TFTs). The a-IGZO:N active layer was deposited by dc reactive sputter with a nitrogen and argon gas mixture at room temperature and performed the superior characteristics while comparing with the intrinsic IGZO TFTs.
Electrical Performance Enhancement of AlZn-SnO Thin Film Transistor by Supercritical Fluid Treatment
(2013-09-01)
Teng, Li-Feng
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Liu, Po-Tsun
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Wang, Wei-Ya
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光電工程學系
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顯示科技研究所
In this letter, a low-temperature supercritical fluid (SCF) treatment was employed to enhance the electrical and optical properties of amorphous Al-Zn-Sn-O thin film transistors (a-AZTO TFTs) for flat-panel displays. The carrier mobility and threshold voltage of a-AZTO TFT were improved significantly after SCF process because of the reduction of trap density in the a-AZTO active layer. In addition, the SCF-treated a-AZTO TFT exhibited superior electrical reliability and less degradation after negative gate bias illumination stress. X-ray photoelectron spectroscopy analysis confirmed that the proposed SCF treatment could effectively oxidize a-AZTO film and change the oxidation states of Sn, resulting in the improvement of a-AZTO TFT device characteristics.
Environment-dependent metastability of passivation-free indium zinc oxide thin film transistor after gate bias stress
(2009-12-07)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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光電工程學系
;
顯示科技研究所
We investigated the effects of bias stress on a passivation-free InZnO thin-film transistors (a-IZO TFTs) exposed to either the atmosphere or a vacuum. The magnitude of threshold voltage shift increased with the application duration of bias stress, to an extent that was much larger in the atmosphere than in the vacuum. The threshold voltage recovered slowly to its nearly initial value when the gate bias stress was removed. The electrical metastability was attributed to the interaction between the exposed a-IZO backchannel and oxygen/moisture from the atmosphere, and a dynamic equilibrium was finally achieved, regardless of the polarity of stress voltage. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3272016]
High-gain complementary inverter with InGaZnO/pentacene hybrid ambipolar thin film transistors
(2010-08-23)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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Fuh, Chur-Shyang
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光電工程學系
Ambipolar thin film transistors (TFTs) with InGaZnO/pentacene heterostructure channels are demonstrated for a high-voltage-gain complementary metal oxide semiconductor (CMOS) inverter. The ambipolar TFT exhibits a electron mobility of 23.8 cm(2)/V s and hole mobility of 0.15 cm(2)/V s for the InGaZnO and pentacene, respectively. The thermal annealing process was also studied to adjust electron concentration reducing operating voltage of the CMOS inverter. The voltage gain achieves as high as 60 obtained in the first and third quadrants of the voltage transfer characteristic. The high performance and simple manufacture of the heterostructure CMOS inverter show promise as critical components in various electrical applications. (C) 2010 American Institute of Physics. [doi:10.1063/1.3483616]
Indium-Gallium-Zinc-Oxide Based Resistive Switching Memory for System-on-Glass Application
(2011)
Fan, Yang-Shun
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Hsu, Ching-Hui
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Teng, Li-Feng
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Yu, Ming-Chang
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Liu, Po-Tsun
A new bipolar resistive random access memory (RRAM) based on amorphous InGaZnO was proposed with one order memory window (high to low resistance state) over two hundreds switching cycles. Besides, a conceptual co-operation scheme was also demonstrated between a-IGZO RRAM and TFT for the system-on-Glass application.
Investigation on Effects of Composition on Transparent Aluminum Zinc Tin Oxide Thin-Film Transistors
(2012-01-01)
Fuh, Chur-Shyang
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Teng, Li-Feng
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Fan, Yang-Shun
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Chang, Chih-Hsiang
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Liu, Po-Tsun
We investigated on electrical performance of amorphous Al-Zn-Sn-O thin film transistor (AZTO TFT). The mobility enhanced while the concentration of Sn increased. The improved stability can be attributed to the increase of Sn concentration and enhancement of bonding energy of metal ion with the increase of O-2 gas flow rate.
Nitrogenated amorphous InGaZnO thin film transistor
(2011-01-31)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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Li, Fu-Hai
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Shieh, Han-Ping
This work presents the electrical characteristics of the nitrogenated amorphous InGaZnO thin film transistor (a-IGZO:N TFT). The a-IGZO: N film acting as a channel layer of a thin film transistor (TFT) device was prepared by dc reactive sputter with a nitrogen and argon gas mixture at room temperature. Experimental results show that the in situ nitrogen incorporation to IGZO film can properly adjust the threshold voltage and enhance the ambient stability of a TFT device. Furthermore, the a-IGZO: N TFT has a 44% increase in the carrier mobility and electrical reliability and uniformity also progress obviously while comparing with those not implementing a nitrogen doping process. (C) 2011 American Institute of Physics. [doi:10.1063/1.3551537]
Photosensor application of amorphous InZnO-based thin film transistor
(2010)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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光電工程學系
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Department of Photonics
Thin film transistor (TFT) device structure with transparent conductive oxide semiconductor is proposed for the photosensor application. The adoption of TFT-based photosensor device also is promising to be integrated with pixel-array circuits in a flat panel display and realize the system-on-panel (SoP) concept. The photosensitive TFT device can be applied to sense the ambient light brightness and then give the feedback to the backlight system adjusting the backlight intensity for the power-saving green displays. In this work, we studied the photosensitivity of amorphous indium zinc oxide (a-IZO) TFT to ultraviolet light. The a-IZO-based semiconductors have been paid much attention due to their uniform amorphous phase and high field-effect carrier mobility characteristics. The obvious threshold voltage shift was observed after light illumination, and exhibited slow recovery while returning to initial status after removing the light source. This mechanism for the photoreaction is well explained by the dynamic equilibrium of charge exchange reaction between O(2(g)) and O(2)(-) in the backchannel region of IZO-based films. An electrical trigger using charge pumping method is used to confirm the proposed mechanism and accelerate photoreaction recoverability for the first time. Using knowledge of photoreaction behavior, an operation scheme of photosensing elements consist of a-IZO TFTs is also demonstrated in this paper.
Reduced parasitic contact resistance and highly stable operation in a-In-Ga-Zn-O thin-film transistors with microwave treatment
(2016-11-30)
Liu, Po-Tsun
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Chang, Chih-Hsiang
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Zheng, Guang-Ting
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Fuh, Chur-Shyang
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Teng, Li-Feng
In this work, we studied the effects of microwave annealing process on amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) and demonstrated a high performance and reliable device characteristics. The characteristic trapping time (tau) derived from stretched-exponential model was extracted to exhibit the quality improvement of a-IGZO thin film. The microwave annealing features a selective heating and potentially avoids the damage to materials neighboring the a-IGZO channel layer in TFT device structure during thermal processes, resulting in lower parasitic source to drain resistance. (C) 2016 Elsevier B.V. All rights reserved.
Retarded Photoreaction Reversibility of a-IZO TFT for Light Sensor Applications
(2009)
Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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Chu, Chun Hung
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Shieh, Han-Ping D.
The retarded photoreaction reversibility of a-IZO TFT has been discussed in this work. With a small DC voltage bias, the reaction was speeded up and the electrical characteristics were recovered back to the fresh state. The V(th) shifting behavior possesses the potential for the light sensor applications in display technologies.
Role of environmental and annealing conditions on the passivation-free in-Ga-Zn-O TFT
(2011-12-30)
Fuh, Chur-Shyang
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Sze, Simon Min
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Liu, Po-Tsun
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Teng, Li-Feng
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Chou, Yi-Teh
We examined the characteristics of passivation-free amorphous In-Ga-Zn-O thin film transistor (a-IGZO TFT) devices under different thermal annealing atmospheres. With annealing at higher temperature, the device performed better at the above-threshold operation region, which indicated the film quality was improved with the decrease of defects in the a-IGZO active region. The mobility, threshold voltage and subthreshold swing of a-IGZO TFT annealed at 450 degrees C was 7.53 cm(2)/V s, 0.71 V and 0.18 V/decade, respectively. It was also observed that the a-IGZO was conductive after thermal annealing in the vacuum, due to the ease of oxygen out-diffusion from the a-IGZO back channel. The oxygen deficiency resultantly appeared, and provided leaky paths causing electrical unreliability when TFT was turned off. In contrast, the annealing atmosphere full of O(2) or N(2) would suppress the oxygen diffusion out of the a-IGZO back channel. The worst Vth degradation of a-IGZO TFT after positive gate bias stress and negative gate bias stress (NGBS) was about 2 V and -2 V, respectively. However, the V(th) shift in the NGBS testing could be suppressed to -0.5 V in vacuum chamber. Material analysis methods including X-ray photoelectron spectroscopy and scanning electron microscopy were used to investigate the change of a-IGZO film after different thermal annealing treatments. The variation of O 1s spectra with different annealing atmospheres showed the consistence with our proposed models. (C) 2011 Elsevier B.V. All rights reserved.
Role of Oxygen in Amorphous In-Ga-Zn-O Thin Film Transistor for Ambient Stability
(2013)
Fuh, Chur-Shyang
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Liu, Po-Tsun
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Chou, Yi-Teh
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Teng, Li-Feng
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Sze, S. M.
The role of oxygen in amorphous InGaZnO thin film transistor (a-IGZO TFT) is studied for the device ambient stability. The threshold voltage (Vth) value of 350 degrees C annealed a-IGZO TFT decreased apparently with the staying duration, and the average value shifted from 10.2 V to 5.8 V after a 9-day staying at the atmosphere. After raising the annealing temperature to 450 degrees C, the electrical stability issue was improved significantly with superior electrical parameters, including low threshold voltage (V-th), low subthreshold swing, high carrier mobility and a small V-th variation of +/- 0.5 V. It can be attributed to the enhancement of bonding energy of oxygen in the thermally-annealed a-IGZO film with the increase of thermal annealing temperatures. Besides, the stronger oxygen bonding could also suppress the absorption/desorption and UV-induced migration at the back surface, causing better electrical reliability and immunity against UV radiation, respectively. All these results showed the ambient stability is greatly related to the oxygen in a-IGZO film, and the desired electrical characteristic can be achieved via the optimization of thermal annealing process. (C) 2012 The Electrochemical Society. All rights reserved.
Transparent Amorphous Oxide Semiconductors for System on Panel Applications
(2012)
Liu, Po-Tsun
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Chu, Li-Wei
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Teng, Li-Feng
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Fan, Yang-Shun
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Fuh, Chur-Shyang
We demonstrate the applications of amorphous InGaZnO thin film transistor (a-IGZO TFT), extended from the pixel switcher/current driver, gate driver on array (GOA) to resistive random access memory (RRAM) technologies for system-on-panels (SoPs). The high-performance IGZO TFT with mobility of 13.5 cm(2)/Vs is proposed by microwave annealing process at room temperature only for 100 sec. Furthermore, an integrated gate driver scheme with the a-IGZO TFT as backbone is demonstrated in comparison with the amorphous Si TFT backplane. The rise and fall time of a-IGZO gate driver circuits is shorter than that of a-Si TFT gate driver. In addition, the ASK demodulator with a-IGZO TFT is realized successfully, and potentially to be applied for the system of low-frequency RFID tag. The study on a-IGZO RRAM reveals excellent reliability including 1000 times DC sweep endurance, 10(4) pulse endurance, 10(4) s data retention with read disturb immunity. The flexibility of a-IGZO RRAM device is also examined for flexible electronics applications.
Transportation model establishment of InGaZnO for thin film transistor device application
(2010)
Teng, Li-Feng
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Liu, Po-Tsun
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Chou, Yi-Teh
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Fan, Yang-Shun
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光電工程學系
The transportation model of on electrical metastability of a-InGaZnO TFT is established. The generation of oxygen vacancies by the annealing in a vacuum led to an increased loll and large Vth shifts, while N-2 and O-2 ambience effectively improve the device performance. A physical mechanism is also reasonably proposed.