Browsing by Author "Fuh, Chur-Shyang"

Now showing 1 - 14 of 14

Ambient Stability Enhancement of Thin-Film Transistor With InGaZnO Capped With InGaZnO:N Bilayer Stack Channel Layers
(2011-10-01)
Liu, Po-Tsun
;
Chou, Yi-Teh
;
Teng, Li-Feng
;
Li, Fu-Hai
;
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.
Effect of Annealing on Defect Elimination for High Mobility Amorphous Indium-Zinc-Tin-Oxide Thin-Film Transistor
(2014-11-01)
Fuh, Chur-Shyang
;
Liu, Po-Tsun
;
Huang, Wei-Hsun
;
Sze, Simon M.
;
電子工程學系及電子研究所
This letter studies the correlation of postannealing treatment on the electrical performance of amorphous In-Zn-Sn-O thin-film transistor (a-IZTO TFT). The 400 degrees C annealed a-IZTO TFT exhibits a superior performance with field-effect mobility of 39.6 cm(2)/Vs, threshold voltage (V-th) of -2.8 V, and subthreshold swing of 0.25 V/decade. Owing to the structural relaxation by 400 degrees C annealing, both trap states of a-IZTO film and the interface trap states at the a-IZTO/SiO2 interface decrease to 2.16x10(17) cm(-3)eV(-1) and 4.38x10(12) cm(-2) eV(-1), respectively. The positive bias stability of 400 degrees C annealed a-IZTO TFTs is also effectively improved with a Vth shift of 0.92 V.
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
;
Liu, Po-Tsun
;
Teng, Li-Feng
;
Huang, Sih-Wei
;
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.
Effects of Nitrogen on Amorphous Nitrogenated InGaZnO (a-IGZO:N) Thin Film Transistors
(2016-10)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Fuh, Chur-Shyang
;
Liao, Yu-Tei
;
Sze, Simon M.
In this study, the role of nitrogen in the dc-sputtered amorphous indium gallium zinc oxide (a-IGZO):N are explored extensively with a series of nitrogen gas flow rates during IGZO film deposition. The amorphous film structure and the evolution of chemical bondings were confirmed by X-ray diffractometer and X-ray photoelectron spectroscopy spectra analysis. Also, electrical performance and reliability of a-IGZO: N thin-film transistors (TFTs) formed with different nitrogen gas flow rates were analyzed to study the effects of nitrogen on TFT devices. The device performance of a-IGZO: N TFTs can be enhanced with a proper nitrogen doping concentration. However, with excess nitrogen incorporation in the a-IGZO: N channel layer, both electric characteristic and reliability are degraded due to the extra creation of oxygen deficiencies in a-IGZO: N film and easy formation of unstable interface between gate insulator and channel layer, which were confirmed by low-frequency noise measurement. This potential issue of a-IGZO: N TFT characteristics can be effectively released by introducing a post-treatment on the surface of gate dielectric layer. The optimized electrical characteristics of a-IGZO: N TFT can exhibit a carrier mobility of 19.21 cm(2)/V . s, subthreshold swing of 0.26 V/decade and threshold voltage (V-th) of -0.74 V in this study.
Electrical performance and photo-responses enhancement by in situ nitrogen incorporation to amorphous InGaZnO thin-film transistors
(2011)
Teng, Li-Feng
;
Liu, Po-Tsun
;
Fuh, Chur-Shyang
;
Chou, Yi-Teh
;
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.
Enhancement of reliability and stability for transparent amorphous indium-zinc-tin-oxide thin film transistors
(2016-01-01)
Liu, Po-Tsun
;
Chang, Chih-Hsiang
;
Fuh, Chur-Shyang
;
電子工程學系及電子研究所
;
光電工程學系
We studied the influence of the backchannel passivation layer (BPL) on the ambient stability of amorphous indium-zinc-tin-oxide thin-film transistors (a-IZTO TFTs), in which atomic layer deposited (ALD) Al2O3 films and plasma-enhanced chemical vapor deposited (PECVD) SiO2 films were separately used to be the channel passivation layers. It was observed that the BPL deposition process strongly affects device performance and stability. From the results of the extracted activation energy (Eact), the Al2O3 passivation layer can reduce the trap density in localized tail states, which improves the mobility of a-IZTO TFTs. Compared with the SiO2 passivation layer, the Al2O3 passivation process effectively suppresses H injection into the a-IZTO channel layer underneath with secondary ion mass spectrometer analysis. In addition, it is found that the a-IZTO TFT with the Al2O3 passivation layer can enhance resistance against negative bias illumination stress (NBIS), making it reliable for realistic operation in flat panel displays.
High-gain complementary inverter with InGaZnO/pentacene hybrid ambipolar thin film transistors
(2010-08-23)
Liu, Po-Tsun
;
Chou, Yi-Teh
;
Teng, Li-Feng
;
Fuh, Chur-Shyang
;
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]
Investigation on Effects of Composition on Transparent Aluminum Zinc Tin Oxide Thin-Film Transistors
(2012-01-01)
Fuh, Chur-Shyang
;
Teng, Li-Feng
;
Fan, Yang-Shun
;
Chang, Chih-Hsiang
;
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.
InZnSnO-Based Electronic Devices for Flat Panel Display Applications
(2014)
Liu, Po-Tsun
;
Fuh, Chur-Shyang
;
Fan, Yang-Shun
;
Sze, S. M.
;
交大名義發表
This work demonstrates the versatility of amorphous InZnSnO (a-IZTO) oxide semiconductor, covering from the thin film transistor (TFT) to the resistive random accessmemory (RRAM) technologies for system-on-panel applications. The high-performance a-IZTO TFTs with effective carry mobility of 39.6 cm(2)/V s, threshold voltage of -0.28 V and subthreshold swing of 0.25 decade/V are obtained in this study. Thermal post-annealing also was used to provide stable electrical characteristics with a few threshold voltage shift after positive gate bias stress. On the other hand, the RRAM device with a-IZTO film acting as active layer exhibits superior bipolar resistive switching characteristics. The wide (>10) resistance window and the stability endurance of hundreds cycle are achieved. Both of the proposed a-IZTO TFT and RRAM have promising potential to be integrated with a-IZTO-based periphery electronic circuits for flat-panel display applications. (c) 2014 The Electrochemical Society. All rights reserved.
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
;
Chang, Chih-Hsiang
;
Zheng, Guang-Ting
;
Fuh, Chur-Shyang
;
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.
Role of environmental and annealing conditions on the passivation-free in-Ga-Zn-O TFT
(2011-12-30)
Fuh, Chur-Shyang
;
Sze, Simon Min
;
Liu, Po-Tsun
;
Teng, Li-Feng
;
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
;
Liu, Po-Tsun
;
Chou, Yi-Teh
;
Teng, Li-Feng
;
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.
Thin Film Transistor with Al-Ni-La Alloy Gate Metallization Technology
(2011)
Liu, Po-Tsun
;
Chou, Yi-Teh
;
Hsu, Ting-Hao
;
Fuh, Chur-Shyang
;
平面顯示技術碩士學位學程
In this study, an aluminum-nickel-lanthanum (Al-Ni-La) alloy is introduced, for the first time, to hydrogenated amorphous silicon thin film transistor (a-Si: H TFT) for gate metallization technology. Ni atoms in Al-Ni-La can effectively improve contact characteristic with ITO film, while La can increase the uniformity of contact resistance during film deposition compared to the conventional Al-Nd alloy. Besides, Al-Ni-La alloy has advantages of a simple process and better prevention against hillock issues, which benefits active matrix liquid-crystal display (AMLCD) manufacture. The Al-Ni-La gate thin film transistor (TFT) also exhibited reliable electrical characteristics. The process compatibility with typical TFT manufacture makes Al-Ni-La gate metallization greatly promising for AMLCD technology application. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3516178] All rights reserved.
Transparent Amorphous Oxide Semiconductors for System on Panel Applications
(2012)
Liu, Po-Tsun
;
Chu, Li-Wei
;
Teng, Li-Feng
;
Fan, Yang-Shun
;
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.