Browsing by Author "Yang, Po-Yu"

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A collaborated computing system by web services based P2P architecture
(2006)
Tsai, Min-Jen
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Wang, Chen-Sheng
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Yang, Po-Yu
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Yang, Chien-Yu
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資訊管理與財務金融系註：原資管所+財金所
The peer-to-peer (P2P) model which shares the content or resources over the network gradually replaces the traditional client/server architecture. A new computing architecture: Computing Power Services (CPS) which utilizes Web Services and Business Process Execution Language (BPEL) to overcome the problems of P2P about flexibility, compatibility and workflow management is proposed in this study. CPS is a lightweight Web Services based P2P power sharing environment, and suitable for enterprise computing works which are able to run in batch format in a trusty network. The architecture relies on BPEL which provides a visualized development environment and workflow control management. In this paper, the collaborated computing system has been applied to analyze the robustness of digital watermark by filter bank selection. As the result of this case, the performance can be improved in the aspect of speedup, efficiency and process time.
A Novel Coaxial-Structured Amorphous-Silicon p-i-n Solar Cell With Al-Doped ZnO Nanowires
(2011-07-01)
Li, Hung-Hsien
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Yang, Po-Yu
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Chiou, Si-Ming
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Liu, Han-Wen
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Cheng, Huang-Chung
A novel coaxial-structured amorphous-silicon (a-Si) p-i-n solar cell with 1-mu m-long low-temperature hydrothermally synthesized Al-doped-ZnO (AZO) nanowires was demonstrated for the first time. The conversion efficiency. increased from 3.92% to 4.27% when the intrinsic a-Si thickness was increased from 25 to 150 nm and then decreased to 3.66% when the intrinsic layer thickness was further increased to 250 nm. It was attributed to an excessively thick intrinsic a-Si layer that would decrease the internal electrical field and interfere with charge separation. With the optimum intrinsic a-Si thickness of 150 nm, the conversion efficiency increased from 4.27% to 4.73% when the AZO wire length was increased from 1 to 2 mu m. Moreover, the proposed coaxial-structured solar cell exhibited a nearly 46% efficiency enhancement over a conventional a-Si thin-film solar cell.
A Novel SONOS Memory With Recessed-Channel Poly-Si TFT via Excimer Laser Crystallization
(2012-04-01)
Lee, I-Che
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Tsai, Chun-Chien
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Kuo, Hsu-Hang
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Yang, Po-Yu
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Wang, Chao-Lung
A silicon-oxide-nitride-oxide-silicon memory with recessed-channel (RC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) via excimer-laser crystallization (ELC) has been demonstrated to achieve a high mobility of similar to 400 cm(2)/V . s and a large ON/OFF current ratio of similar to 10(8). Such a high performance is because the RC poly-Si TFTs possess only one perpendicular grain boundary (GB) in the channel and the corresponding protrusion at this GB. In addition, the proposed devices also exhibited the largest memory window of 2.63 V in 10 ms with respect to 2.37 and 1.31 V for the conventional-ELC and solid-phase-crystallized ones, respectively. Since the silicon grain growth could be artificially controlled, the device-to-device uniformity could be significantly improved. Therefore, such a simple scheme is promising for applications of low-temperature poly-Si TFTs in 3-D ICs and system on panel.
Application of supercritical fluids for amorphous silicon thin film transistors
(2006-01-01)
Tsai, Chih-Tsung
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Chang, Ting-Chang
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Liu, Po-Tsun
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Yang, Po-Yu
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光電工程學系
Supercritical fluid technology([1,2]) is employed for the first time to passivate the defect states in amorphous silicon thin film transistors (a-Si.-H TFTs) at low temperature (150 degrees C). Due to supercritical fluids have gas-like properties of diffusivity and viscosity that allow it to efficiently carry H2O molecule into amorphous thin film and passivates defects at low temperature, Experiment results indicate that superior transfer characteristic is obtained and the density of states (DOS) is reduced significantly after the treatment of supercritical fluids mixed with water/propyl alcohol.
Coaxial-structured ZnO/silicon nanowires extended-gate field-effect transistor as pH sensor
(2013-02-01)
Li, Hung-Hsien
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Yang, Chi-En
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Kei, Chi-Chung
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Su, Chung-Yi
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Dai, Wei-Syuan
An extended-gate field-effect transistor (EGFET) of coaxial-structured ZnO/silicon nanowires as pH sensor was demonstrated in this paper. The oriented 1-mu m-long silicon nanowires with the diameter of about 50 nm were vertically synthesized by the electroless metal deposition method at room temperature and were sequentially capped with the ZnO films using atomic layer deposition at 50 degrees C. The transfer characteristics (I-DS-V-REF) of such ZnO/silicon nanowire EGFET sensor exhibited the sensitivity and linearity of 46.25 mV/pH and 0.9902, respectively for the different pH solutions (pH 1-pH 13). In contrast to the ZnO thin-film ones, the ZnO/silicon nanowire EGFET sensor achieved much better sensitivity and superior linearity. It was attributed to a high surface-to-volume ratio of the nanowire structures, reflecting a larger effective sensing area. The output voltage and time characteristics were also measured to indicate good reliability and durability for the ZnO/silicon nanowires sensor. Furthermore, the hysteresis was 9.74 mV after the solution was changed as pH 7 -> pH 3 -> pH 7 -> pH 11 -> pH 7. (C) 2012 Elsevier B.V. All rights reserved.
Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method
(2014-08-29)
Tsai, Wan-Lin
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Wang, Kuang-Yu
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Chang, Yao-Jen
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Li, Yu-Ren
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Yang, Po-Yu
For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400 degrees C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Omega/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.
Design of Novel Field Programmable Gate Array-Based Hearing Aid
(2019-01-01)
Lin, Bor-Shing
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Yang, Po-Yu
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Liu, Ching-Feng
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Huang, Yi-Chia
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Liu, Chengyu
Hearing loss is one of the most common chronic diseases. For people with hearing loss, communicating with other people, particularly in an environment with considerable background noise, is difficult. Recently, several hearing aids have been developed to improve speech comprehension in a noisy environment. The use of an adaptive beamformer is one of the alternative methods for improving speech intelligibility. However, the adaptive beamformer requires the location of the desired speaker to estimate the time differences of arrival (TDOAs) of speech sources to numerous spatially separated sensors in acoustics. In general, the technique of steered response power source localization was used to estimate the TDOA; however, this technique was easily affected by environmental reverberation. To overcome the aforementioned concern, a novel hearing aid is proposed in this paper. By using an image processing technology, the location of the desired speaker could be manually selected to provide precise information on the TDOA. Moreover, adaptive signal enhancements were implemented in a field-programmable gate array to enhance the speech of interest in real time. The experimental results indicate that the proposed system could improve speech intelligibility in various noisy environments. Therefore, the proposed system may be employed to improve the daily lives of people with hearing the loss in the future.
Effect of Oxygen Annealing on the Ultraviolet Photoresponse of p-NiO-Nanoflower/n-ZnO-Nanowire Heterostructures
(2011-07-01)
Yang, Po-Yu
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Wang, Jyh-Liang
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Tsai, Wei-Chih
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Wang, Shui-Jinn
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Lin, Jia-Chuan
A transparent ultraviolet (UV) sensor using nanoheterojunctions (NHJs) composed of p-type NiO nanoflowers (NFs) and n-type ZnO nanowires (NWs) was prepared through a sequential low-temperature hydrothermal-growth process. The devices that were annealed in an oxygen (O(2)) ambient exhibited better rectification behavior (l(forward)/l(reverse) = 427), a lower forward threshold voltage (V(th) = 0.98 V), a lower leakage current (1.68 x 10(-5) A/cm(2)), and superior sensitivity (l(UV)/l(dark) = 57.8; l(visible)/l(dark) = 1.25) to UV light (lambda = 325 nm) than the unannealed devices. The remarkably improved device performances and optoelectronic characteristics of the annealed p-NiO-NF/n-ZnO-NW NHJs can be associated with their fewer structural defects, fewer interfacial defects, and better crystallinity. A stable and repeatable operation of dynamic photoresponse was also observed in the annealed devices. The excellent sensitivity and repeatable photoresponse to UV light of the hydrothermally grown p-NiO-NF/n-ZnO-NW NHJs annealed in a suitable O(2) ambient indicate that they can be applied to nano-integrated optoelectronic devices.
Effect of oxygen plasma treatment on horizontally aligned carbon nanotube thin film as pH-sensing membrane of extended-gate field-effect transistor
(2015-04-01)
Wang, Kuang-Yu
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Tsai, Wan-Lin
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Yang, Po-Yu
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Chou, Chia-Hsin
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Li, Yu-Ren
The high-performance pH-sensing membrane of extended-gate field-effect transistors (EGFET) composed of high-conductivity horizontally aligned carbon nanotube thin films (HACNTFs) after oxygen plasma treatment is successfully demonstrated. The 10-mu m-wide catalytic metal lines with 60 mu m interspace produced CNT vertical plates, and the plates were mechanically pulled down and densified to form HACNTFs. A large amount of oxygen-containing functional groups are decorated on the CNTs after the oxygen plasma treatment. These functional groups act as the sensing sites and respond to the H+ or OH- ions in solutions with different pH values. Therefore, these functionalized HACNTFs as pH-EGFET-sensing membranes can achieve a high voltage sensitivity of 40 mV/pH and high current sensitivity of 0.78 mu A(1/2)/pH. Moreover, large linearity of 0.998 is measured in a wide sensing range from pH 1 to 13. These results reveal that the oxygen plasma treatment is an effective way to improve the CNT-sensing characteristics in pH-EGFET sensors. (C) 2015 The Japan Society of Applied Physics
Effect of the Annealing Ambient on the Electrical Characteristics of the Amorphous InGaZnO Thin Film Transistors
(2012-07-01)
Huang, Yu-Chih
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Yang, Po-Yu
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Huang, Hau-Yuan
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Wang, Shui-Jinn
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Cheng, Huang-Chung
The influence of the thermal annealing on the amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) under different ambient gases has been systematically addressed. The chemical bonding states and transfer characteristics of a-IGZO TFTs show evident dependence on the annealing ambient gas. For the a-IGZO TFTs in the oxygen ambient annealing at 250 degrees C for 30 mins exhibited a maximum field effect mobility (max mu(FE)) of 9.36 cm(2)/V . s, on/off current ratio of 6.12 X 10(10), and a subthreshold slope (SS) of 0.21 V/decade. Respectively, the as-deposited ones without annealing possess a max mu(FE) of 6.61 cm(2)/V . s, on/off current ratio of 4.58 x 10(8), and a SS of 0.46 V/decade. In contrast, the a-IGZO TFTs annealed at 250 degrees C for 30 mins in the nitrogen ambient would be degraded to have a max mu(FE) of 0.18 cm(2)/V . s, on/off current ratio of 2.22 X 10(4), and a SS of 7.37 V/decade, corresponding. It is attributed to the content of the oxygen vacancies, according the x-ray photoelectron spectroscopy (XPS) analyze of the three different samples.
Effects of crystallization mechanism on the electrical characteristics of green continuous-wave-laser-crystallized polycrystalline silicon thin film transistors
(2013-07-29)
Chou, Chia-Hsin
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Lee, I-Che
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Yang, Po-Yu
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Hu, Ming-Jhe
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Wang, Chao-Lung
Thin film transistors (TFTs) with amorphous silicon films crystallized via continuous-wave green laser at a wavelength of 532 nm exhibit very different electrical characteristics in various crystallization regions, corresponding to the Gaussian energy density distribution of the laser beam. In the center region subjected to the highest energy density, the full melting scheme led to the best crystallinity of the polycrystalline silicon film, resulting in the highest field-effect mobility of 500 cm(2) V-1 s(-1). In contrast, the edge region that resulted in solid phase crystallization exhibited the worst mobility of 48 cm 2 V-1 s(-1) for the polycrystalline silicon TFTs. (C) 2013 AIP Publishing LLC.
Effects of supercritical CO2 fluid on sputter-deposited hafnium oxide
(2007-05-28)
Liu, Po-Tsun
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Tsai, Chih-Tsung
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Yang, Po-Yu
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光電工程學系
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顯示科技研究所
Low-temperature supercritical fluid (SCF) technology is employed to improve the dielectric characteristics of metal oxide film deposited at low temperature. In this investigation, hafnium oxide (HfO2) film was sputter deposited at room temperature and post-treated with SCF at 150 degrees C, replacing typical high-temperature annealing process. From Fourier transformation infrared and thermal desorption spectroscopy measurement, the absorption peaks of Hf-O-Hf bonding and the oxygen content in HfO2 film have, respectively, shown apparent raise. The leakage current density of the low-temperature deposited HfO2 film is reduced significantly, and the conduction mechanism is modified from trap-assisted quantum tunneling to thermionic emission process, since SCF treatment effectively reduces the number of traps in HfO2 film. (C) 2007 American Institute of Physics.
Enhanced efficiency of the dye-sensitized solar cells by excimer laser irradiated carbon nanotube network counter electrode
(2014-02-03)
Chien, Yun-San
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Yang, Po-Yu
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Lee, I-Che
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Chu, Chih-Chieh
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Chou, Chia-Hsin
The carbon nanotube network decorated with Pt nanoparticles (PtCNT) irradiated by excimer laser as counter electrode (CE) of dye-sensitized solar cells (DSSCs) has been systematically demonstrated. The conversion efficiency would be improved from 7.12% to 9.28% with respect to conventional Pt-film one. It was attributed to the enhanced catalytic surface from Pt nanoparticles and the improved conductivity due to the adjoining phenomenon of PtCNTs irradiated by laser. Moreover, the laser annealing could also promote the interface contact between CE and conductive glass. Therefore, such a simple laser-irradiated PtCNT network is promising for the future flexible DSSCs applications. (C) 2014 AIP Publishing LLC.
Field Emission Properties of Carbon Nanotube Arrays on the Thickness-Controlled Flexible Substrate by the Pattern Transfer Process
(2012-07-01)
Chang, Chia-Tsung
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Juan, Chuan-Ping
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Lin, Yi-Chan
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Li, Yu-Ren
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Tsai, Wan-Lin
A technigal with the polydimethylsiloxane (PDMS) solution infiltrated into the SiOx-coated CNTAs has been utilized to directly transfer the CNTAs away from the silicon substrate. The oxide coating layer was utilized to protect the morpholgy of as-grown patterned vertical aligmed carbon nanotube (CNTs) arrays. The high density plasma reactive ions etching (HDP-RIE) system was used to make the CNTs emerge from the surface of the flexible substrate and modify the crystallines of CNTs. After the protecting oxide was HDP-RIE-processed for 8 min, the emission current properties were enhanced to be 1.03 V/mu m and 1.43 V/mu m, respectively, for the turn-on field and the threshold field, as compared with 1.25 V/mu m and 1.59 V/mu m for the as-grown CNTs, accordingly. The Field Emission (FE) enhancement after dry etching could be attributed to the open-ended structures and better crystalline.
Field-Emission Characteristics of Al-Doped ZnO Nanostructures Hydrothermally Synthesized at Low Temperature
(2011-07-01)
Yang, Po-Yu
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Wang, Jyh-Liang
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Tsai, Wei-Chih
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Wang, Shui-Jinn
;
Lin, Jia-Chuan
The aluminum-doped ZnO (AZO) nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at a temperature as low as 85 degrees C. The morphologies, crystallinity, optical emission properties, and chemical bonding states of AZO nanostructures show evident dependence on the aluminum dosage. The morphologies of AZO nanostructures were changed from vertically aligned nanowires (NWs), and NWs coexisted with nanosheets (NSs), to complete NSs in respect of the Al-dosages of 0 similar to 3 at.%, 5 at.%, and 7 at.%, correspondingly. The undoped ZnO and lightly Al-doped AZO (<= 3 at.%) NWs are single-crystalline wurtzite structure. In contrast, heavily Al-doped AZO sample is polycrystalline. The AZO nanostructure with 3 at.% Al-dosages reveals the optimal crystallinity and less structural defects, reflecting the longest carrier lifetime and highest conductivity. Consequently, the field-emission characteristics of such an AZO emitter can exhibit the higher current density, larger field-enhancement factor (beta) of 3131, lower turn-on field of 2.17 V/mu m, and lower threshold field of 3.43 V/mu m.
Field-Emission Characteristics of Zinc Oxide Nanowires Using Low-Temperature Supercritical Carbon Dioxide Fluid Method
(2012-01-01)
Yang, Po-Yu
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Agarwal, Sanjay
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Cheng, Huang-Chung
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材料科學與工程學系
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電子工程學系及電子研究所
Single-crystalline ZnO nanowires (NWs) were directly grown on Zn/glass substrates by using a low-temperature (i.e., 40 degrees C) supercritical carbon dioxide (SCCO(2)) fluid method. The optical, physical, and field-emission (FE) characteristics of the SCCO(2)-synthesized ZnO nanostructures are systematically investigated. ZnO NWs exhibited the low turn-on field of 3.16 V/mu m at a current density of 10 mu A/cm(2) and a low threshold field of 4.38 V/mu m at a current density of 1 mA/cm(2). The current fluctuation of ZnO emitters was less than 8% at 5.3 V/mu m in 12 h. The excellent FE properties of SCCO(2)-synthesized ZnO emitters at low temperature make them a superior candidate for FE-based display devices.
Field-Emission Stability of Hydrothermally Synthesized Aluminum-Doped Zinc Oxide Nanostructures
(2012-07-01)
Hsieh, Tsang-Yen
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Wang, Jyh-Liang
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Yang, Po-Yu
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Hwang, Chuan-Chou
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Shye, Der-Chi
The Al-doped ZnO (AZO) nanostructures field-emission arrays (FEAs) were hydrothermally synthesized on AZO/glass substrate. The samples with Al-dosage of 3 at.% show the morphology as nanowires vertically grown on the substrates and a structure of c-axis elongated single-crystalline wurtzite. The good field-emission (i.e., the large anode current and low fluctuation of 15.9%) can be found by AZO nanostructure FEAs with well-designed Al-dosage (i.e., 3 at.%) because of the vertical nanowires with the less structural defects and superior crystallinity. Moreover, the Full width at half maximum (FWHM) of near band-edge emission (NBE) decreased as the increase of annealing temperature, representing the compensated structural defects during oxygen ambient annealing. After the oxygen annealing at 500 degrees C, the hydrothermal AZO nanostructure FEAs revealed the excellent electrical characteristics (i.e., the larger anode current and uniform distribution of induced fluorescence) and enhanced field-emission stability (i.e., the lowest current fluctuation of 5.97%).
Flexible Atmospheric-Pressure Gas Ionization Sensors with Horizontally Aligned Carbon Nanotube Electrodes
(2016-12)
Wang, Kuang-Yu
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Tsai, Wan-Lin
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Yang, Po-Yu
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Chou, Chia-Hsin
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Liao, Chan-Yu
A flexible atmospheric-pressure gas ionization sensor (GIS) with the horizontally aligned carbon nanotube (HACNT) electrodes in the planar structure has been demonstrated for the first time via the proposed rolling-down technique of CNTs. The gap between the electrodes of high-density and uniform HACNTs could be therefore precisely controlled via adjusting the length of the CNTs and the interspacing between the patterned catalysts. High-performance sensing characteristics to various gases Ar, N-2, air, and O-2 at atmospheric pressure with the breakdown voltages as low as 160, 193, 205, and 233, respectively, have been achieved with the electrode gap of 20 mu m. It is attributed to the field enhancement from the small gap and the double-side nanostructures. The superior flexibility of the proposed GIS with different bending tests has also been obtained. It reflects that the HACNTs possess excellent material properties, including great mechanical strength and good electrical conductivity. Such a simple, low-cost, and flexible GIS is promising for its applications in portable and wearable personal monitoring devices.
Functionalized Carbon Nanotube Thin Films as the pH Sensing Membranes of Extended-Gate Field-Effect Transistors on the Flexible Substrates
(2014-07-01)
Tsai, Wan-Lin
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Huang, Bai-Tao
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Wang, Kuang-Yu
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Huang, Yu-Chih
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Yang, Po-Yu
The oxygen-plasma-functionalized carbon nanotube thin films on the flexible substrates as the pH sensing membranes of extended-gate field-effect transistors are proposed for the first time. The carbon nanotubes are ultrasonically sprayed onto the polyimide substrates followed by an oxygen-plasma functionalization. Such oxygen-plasma-treated carbon nanotube thin films (CNTFs) exhibit superior pH sensing characteristics with the sensitivity of 55.7 mV/pH and voltage linearity of 0.9996 in a wide sensing range of pH 1-13. Moreover, the excellent flexibility of carbon nanotube is also demonstrated and the oxygen-plasma-treated CNTFs still maintain the sensitivity of 53.6 mV/pH and voltage linearity of 0.9943 even after five-cycle bending test. These results reveal that the oxygen-plasma-treated CNTFs have great potentials in the practically disposal and wearable biosensor applications.
High Field-Emission Stability of Offset-Thin-Film Transistor-Controlled Al-Doped Zinc Oxide Nanowires
(2011-04-01)
Yang, Po-Yu
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Wang, Jyh-Liang
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Tsai, Wei-Chih
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Wang, Shui-Jinn
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Lin, Jia-Chuan
Aluminum-doped zinc oxide (AZO) nanowire (NW) arrays incorporating an offset thin-film transistor (offset-TFT) have been proposed to achieve high field-emission (FE) stability. The AZO NW field emission arrays (FEAs) were hydrothermally grown at a low temperature of 85 degrees C. The uncontrolled AZO NW FEAs demonstrated superior FE characteristics (i.e., turn-on field of similar to 2.17 V/mu m and threshold field of similar to 3.43 V/mu m) compared with those of the conventional CNT FEAs grown at a temperature below 600 degrees C. However, uncontrolled AZO NW FEAs show a larger current fluctuation of 15.6%. Therefore, the offset-TFTs were used to control the AZO NW FEAs. Consequently, the fluctuation of AZO NW FEAs could be significantly reduced to less than 2%. This novel field emission device exhibits good emission stability, low-voltage controllability, low-temperature processing, and structural simplicity, making it promising for applications in flat panel displays. (C) 2011 The Japan Society of Applied Physics