Browsing by Author "Deng, I-Chung"

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A circular CPW-fed slot antenna resonated by the circular loop for broadband circularly polarized radiation
(2008-05-01)
Deng, I-Chung
;
Ke, Qing-Xiang
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Lin, Ren-Jie
;
King, Yueh-Tsu
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電子工程學系及電子研究所
The coplanar waveguide (CPW) fed circular slot antenna, resonated by the circular loop with a narrow opening, is designed for obtaining broadband circularly polarized (CP) radiation. The length of protruded signal strip (L-S) is utilized to adjust the phase difference between two orthogonal field components in the circularly polarized waves. In this design, the proposed antenna has the minimum return loss of -56.5 dB at the frequency of 2.403 GHz. The impedance and 3 dB axial-ratio bandwidths can reach up to 740 MHz or 33.3% and 390 MHz or 16.6%, respectively. In addition, the simulated results are about as good as those of the measured ones. (C) 2008 Wiley Periodicals, Inc.
A novel design of a CPW-fed single square-loop antenna for circular polarization
(2008-09-01)
Deng, I-Chung
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Lin, Ren-Jie
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Ke, Qing-Xiang
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Huang, Jia-Min
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Chang, Kow-Ming
The experimental and simulated results for the proposed antenna are investigated in this article. Moreover, a novel broadband design of a circularly polarized (CP) single square slot antenna fed by a single coplanar waveguide is presented. By appropriately choosing the circumference of the square-loop, the length of the protruded strip, and the gap, this proposed antenna thus owns good CP radiation and good impedance match simultaneously at the frequency of 2.45 GHz. This proposed antenna has the fundamental resonant frequency of 2.5 GHz with the minimum return loss of -39.9 dB. Furthermore, its impedance bandwidth is 460 MHz or 18.4% and 3-dB axial-ratio (AR) bandwidth is 360 MHz or 14.4% at 2.5 GHz.
A novel design of a CPW-fed square slot antenna with broadband circular polarization
(2006-12-01)
Chang, Kow-Ming
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Lin, Ren-Jie
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Deng, I-Chung
;
Chen, Jin-Bo
;
Xiang, Ke Qing
A novel design of a broadband circularly polarized square slot antenna fed by a single coplanar waveguide is proposed and discussed. The circularly polarized radiation is achieved by means of using an outer rectangular ring and an inner rectangular ring at the center of a square slot. The proposed antenna has the fundamental resonant frequency of 2.44 GHz with the return loss of -40.93 dB, and it has the bandwidth of 3 dB axial ratio of 420 MHz or (17.21%). Details of the results are presented and discussed. (c) 2006 Wiley Periodicals, Inc.
A novel design of a microstrip-fed shorted square-ring slot antenna for circular polarization
(2007-07-01)
Chang, Kow-Ming
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Lin, Ren-Jie
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Deng, I-Chung
;
Ke, Qing-Xiang
;
電子工程學系及電子研究所
The design of a circularly polarized slot antenna fed by a single microstrip line is presented. The circularly polarized radiation is achieved by means of using a shorted square-ring slot. This proposed antenna has the fundamental resonant frequency of 2.4 GHz with the minimum return loss of -50.44 dB. The impedance bandwidth is 930 MHz or 38.7% referred to the resonant frequency, and it also has the 3-dB axial-ratio (AR) bandwidth of 310 MHz or 12.9% referred to the resonant frequency. In addition, this proposed antenna shows good performance of circular polarization (CP) radiation with the range of the lower 3-dB AR value covering elevation angles between -40 to 40 degrees. (C) 2007 Wiley Periodicals, Inc.
Characteristics of IGZO TFT Prepared by Atmospheric Pressure Plasma Jet Using PE-ALD Al2O3 Gate Dielectric
(2012-04-01)
Wu, Chien-Hung
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Chang, Kow-Ming
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Huang, Sung-Hung
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Deng, I-Chung
;
Wu, Chin-Jyi
This letter proposes a novel atmospheric pressure plasma jet (APPJ) method for indium-gallium-zinc-oxide (IGZO) deposition and use of the plasma-enhanced atomic layer deposition (PE-ALD) Al2O3 as gate dielectric. A nonvacuum and simple APPJ system was demonstrated for channel material deposition. High-transmittance nanocrystalline IGZO thin films were obtained. Excellent electrical characteristics were achieved, including a low V-T of 0.71 V, a small subthreshold swing of 276 mV/dec, a mobility of 8.39 cm(2)/(V . s), and a large I-on/I-off ratio of 1 x 10(8).
Design of low-temperature CMOS-process compatible membrane fabricated with sacrificial aluminum layer for thermally isolated applications
(2007-03-15)
Chang, Kow-Ming
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Lin, Ren-Jie
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Deng, I-Chung
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In the surface micromachining technique, residual stress and sticking effect play an important role in determining whether a microstructure is suspended or collapse during a release process. In this paper, we propose a simpler method for making suspended membranes for thermally isolated application by using cheap processing steps and compatible with CMOS-process; also, there are some simulations done to predict stiction as function of the anchor profile. It is demonstrated by fabricating the test structures of CMOS-process compatible surface micromachined bolometer using aluminum sacrificial layer with high yield and high throughput. The aluminum sacrificial layer provides some benefits including rapid wet-etching and high wet-etching selectivity with respect to dielectric materials. The residual stress and gravity of the microstructures are evaluated with structural simulations, and the sticking effect can be alleviated by an appropriate structure design and a release process. Once the residual stress is known, we can successfully use Coventorware simulations to predict a suspended membrane by controlling the anchor profile which contains sidewall conformal factor and sidewall angle. The simulation results are in good agreement with the experiments. (c) 2006 Elsevier B.V. All rights reserved.
Electrical Improvement of MIS Capacitor with HfAlOx Gate Dielectrics Treated by Dual Plasma Treatment
(2012)
Deng, I-Chung
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Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
High dielectric constant materials (high-k) such as Hf-based thin films are the promising candidates for 45-nm CMOS technology. It has been described that nitridation processes could improve thermal stability and dielectric constants of Hf-based dielectrics. Furthermore, fluorine incorporation into high-k dielectric was also proposed in order to suppress leakage current and passivate defects. In this study, we examined dual plasma treatment (CF4 pretreatment and N-2 post-treatment) on HfAlOx thin films in order to improve electrical characteristics. Based on our experimental results, HfAlOx Metal-Insulator-Semiconductor (MIS) capacitor properties such as capacitance density, gate leakage current density, and hysteresis could be successfully improved. Compared to untreated samples, capacitance is 42.5% higher and gate leakage is suppressed about three orders when dual plasma treatment is used. According to this study, dual plasma treatment would be an effective technology to improve the electrical characteristic of HfAlOx thin films.
Improvement on Interface Quality and Reliability Properties of HfAlOx MIS Capacitor with Dual Plasma Treatment
(2012)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
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Wu, Chien-Hung
HfO2 is considered a promising gate dielectric material for sub-45 nm CMOS technology. It has been reported that incorporate Al into HfO2 forming Hf aluminates in order to increase the crystallization temperature. However, the growth of the low-k interfacial layer at high-k/Si interface during high-k dielectric deposition would result in reliability degradation. Recently, incorporating nitrogen into HfAlOx gate dielectrics has beneficial effect on reliability performance. In addition, fluorine incorporation into high-k dielectrics also could have several improvements. In this study, dual plasma (CF4 pre-treatment and N-2 post-treatment) was performed on HfAlOx MIS capacitor in order to improve interface quality and the reliability properties. According to our experimental results, dual plasma treatment could improve interface quality and enhance reliability properties of HfAlOx thin films.
Reliability Properties and Current Conduction Mechanisms of HfO2 MIS Capacitor with Dual Plasma Treatment
(2011)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chen, Shou-Hsien
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Deng, I-Chung
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電機工程學系
The incorporation of nitrogen in HfO2 gate dielectrics has been reported to be beneficial for electrical performance. The improvement in the electrical characteristics of HfO2 thin film with plasma nitridation process or plasma fluorination process has also been examined. In this study, dual plasma, CF4 pre-treatment and nitrogen post-treatment, treatments were performed on HfO2 MIS capacitor for further improvement on reliability characteristic. We examine the reliability properties and the current conduction mechanism of HfO2 thin films. The frequency dispersion and constant voltage stress (CVS) characteristics of the samples were analyzed to estimate the improvement. According to the present study, dual plasma treatment could be better than single plasma treatment and would be an effective approach for HfO2 dielectric improvement.
The effect of oxygen species on the ZnO TFT prepared by atmosphere pressure plasma jet
(2012)
Wu, Chien-Hung
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Chang, Kow-Ming
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Huang, Sung-Hung
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Deng, I-Chung
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Chi, Chia-Wei
Bottom-gate thin-film transistors (TFTs) were fabricated with ZnO channel layer deposited by atmospheric pressure plasma jet (APPJ). The effect of oxygen partial pressure on the ZnO TFT was investigated. The ZnO thin films were deposited at 100 degrees C, and oxygen gas was incorporated into plasma gas (N-2) in the percentage of 0%-1% (O-2/N-2+O-2). Reactive oxygen species could repair the oxygen vacancies during deposition, and the switching behavior was improved effectively. With increasing oxygen partial pressure, the ZnO thin films exhibited a more random orientation. By incorporating 0.69% O-2 into plasma gas, a threshold voltage of 26.7 V, a subthreshold swing of 3.89 V/decade, a field-effect mobility of 2.38 cm(2)/Vs and an I-on/I-off current ratio of 4.63x10(9) were obtained.
The effect of thermal annealing on the properties of IGZO TFT prepared by atmospheric pressure plasma jet
(2012)
Wu, Chien-Hung
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Chang, Kow-Ming
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Huang, Sung-Hung
;
Deng, I-Chung
;
Wu, Chin-Jyi
We fabricated bottom gate TFTs with IGZO channel layer deposited by atmospheric pressure plasma jet (APPJ). The effect of thermal annealing on the properties of IGZO TFTs was studied. After post annealing, the IGZO thin films showed a smooth and dense structure. The transistors annealed at 300 degrees C showed clear switching behavior with a negative threshold voltage of -0.571 V and a mobility of 2.6 cm(2)/V-s. After 500 degrees C post annealing, IGZO thin film showed an amorphous-like phase and the average transmittance is more than 80% in the visible range. Good electrical characteristics were achieved, including a threshold voltage of 6.74V, a subthreshold swing of 1.54 V/dec, a mobility of 10.31 cm(2)/V-s and a large I-on/I-off ratio of 3.28x10(8).
Using dual plasma treatment to improve electrical characteristics and reduce flicker noise of high-kappa HfO2 LTPS-TFTs
(2015-09-01)
Chang, Kow-Ming
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Huang, Bo-Wen
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Wu, Chien-Hung
;
Deng, I-Chung
;
Chang, Ting-Chia
This study demonstrated the application of a dual plasma treatment to low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) comprising a self-aligned phosphorus implantation source and drain, high-kappa HfO2 gate dielectric, and aluminum metal gate. The dual plasma treatment involves a pre-deposition CF4 plasma treatment at a high-kappa/poly-Si interface and post-deposition N-2 plasma treatment at a high-kappa HfO2 gate dielectric; this treatment enables reducing the interface-trap-state defects at the high-kappa/poly-Si interface, grain boundary traps in the poly-Si channel film, and oxygen vacancy V-o in the high-kappa HfO2 gate dielectric. Thus, LTPS-TFTs with dual plasma treatment demonstrate excellent electrical characteristics such as threshold voltage, subthreshold swing, transconductance, driving current, and on/off current ratio. Flicker noise, also referred to as 1/f noise, caused by fluctuations of carriers transported in the grain boundary and the trapped carriers per unit oxide volume (N-t) can be suppressed. Therefore, high performance LTPS-TFTs subjected to dual plasma treatment can be appropriately applied to active matrix liquid phase-crystal display on system-on-panel technology. (C) 2015 Elsevier Ltd. All rights reserved.