Browsing by Author "Tsai, H. H."

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A Full-Color, White Light Emission of Quantum-Dot-Based Display Technology Using Pulsed Spray Method with Distributed Bragg Reflector
(2012)
Chen, K. J.
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Chen, H. C.
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Lin, C. C.
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Tsai, H. H.
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Tsai, K. A.
A colloidal quantum dot light-emitting multi-layer structure with HFO2/SiO2 distributed Bragg reflector is manufactured by pulse spray method. A pure white light with strong enhancement due to better utilization of UV pump was demonstrated. (C)2012 Optical Society of America
Effect of the Thermal Characteristics of Phosphor for the Conformal and Remote Structures in White Light-Emitting Diodes
(2013-10-01)
Chen, K. J.
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Lin, B. C.
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Chen, H. C.
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Shih, M. H.
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Wang, C. H.
The influence of the thermal effect of phosphor for conformal and remote structures in white light-emitting diodes was investigated using the junction and phosphor temperatures. Comparing the measured temperatures with IR thermometer, the remote structure has a higher phosphor temperature than the conformal structure. This result indicates that the phosphor in the conformal structure has demonstrated superior conduction because of the high thermal conductivity in surrounding. Furthermore, thermal distribution in the simulation results has shown to have favorable agreement with the experimental results. Consequently, the lifetime measurement is shown to verify the results of the simulation and experiment for both structural types.
Improvement of Angular-dependent CCT Uniformity by ZrO2 Nano-particles in Remote Phosphor White LEDs
(2012)
Chen, H. C.
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Chen, K. J.
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Wang, C. H.
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Tsai, H. H.
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Lin, C. C.
The superior uniformity of angular-dependent CCT white LEDs have been investigated by ZrO2-type remote phosphor structure. This novel structure reduces angular-dependent CCT deviations from 1000K to 420K in range of -70 to 70 degrees. (C)2012 Optical Society of America
Improvement of lumen efficiency in white light-emitting diodes with air-gap embedded package
(2012-05-01)
Chen, H. C.
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Chen, K. J.
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Lin, C. C.
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Wang, C. H.
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Yeh, C. C.
In this paper, white light-emitting diodes (LEDs) with air-gap embedded package were proposed and fabricated by a simple method including pulsed spray coating. The lumen efficiency of air-gap embedded LED was enhanced by 8.8% at driving current of 350 mA, compared to conventional remote phosphor white LED. This improvement was due to the enhanced utilization of blue and yellow rays, which were confirmed by pulse current-dependent correlated color temperature (CCT). The utilization efficiency of blue rays was enhanced by 12.4% due to the embedded air-gap layer. The simulation results performed by Monte-Carlo ray tracing method agreed with our experiments, which showed enhancement in lumen efficiency and similar CCT. Finally, the electric field intensity versus different thickness for air-gap and no air-gap embedded white LED was calculated to check the incident blue rays trapped in phosphor layer. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
Operations of poly-Si nanowire thin-film transistors with a multiple-gated configuration
(2007-05-30)
Su, C. J.
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Lin, H. C.
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Tsai, H. H.
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Hsu, H. H.
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Wang, T. M.
In this study, a novel multiple-gated (MG) thin-film transistor (TFT) with poly-Si nanowire ( NW) channels is fabricated using a simple process flow. In the proposed new transistors, poly-Si NWs were formed in a self-aligned manner and were precisely positioned with respect to the source/drain, and the side-gate. Moreover, the NW channels are surrounded by three gates, i.e., top-gate, side-gate and bottom-gate, resulting in much stronger gate controllability over the NW channels, and greatly enhanced device performance over the conventional single-gated TFTs. Furthermore, the independently applied top-gate and/or bottom-gate biases could be utilized to adjust the threshold voltage of NW channels in a reliable manner, making the scheme suitable for practical applications.
Structural and optical properties of Al-doped ZnO nanowires synthesized by hydrothermal method
(2007-12-03)
Bai, S. N.
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Tsai, H. H.
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Tseng, T. Y.
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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
The growth of one dimensional Al-doped ZnO nanowires on a silicon substrate with a ZnO seeding layer by using a low temperature hydrothermal method is demonstrated. The structural and optical characteristics of the solution-grown Al-doped ZnO nanowires were studied using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and cathodoluminescence (CL) measurements. The FE-SEM images show that the ZnO nanowires are hexagonal column shaped and stand perpendicularly on the silicon substrate. It is found in XRD patterns that the ZnO nanowires annealed at various temperatures are all wurtzite crystal structure and have (002) preferred orientation. As the annealing temperature changed, the intensity of (100) and (10 1) peaks reveals distinct change. The CL spectra show the as-grown ZnO nanowires display a weak and narrow UVemission centered at 376 nm. A strong and very broad green-yellow emission band with a center at 575 nm as well as a shoulder like orange-red emission band centering at 625 nm is also demonstrated. It is shown that the luminescence intensity centered at 376 nm increased, the shoulder like emission centered at 625 nm decreased but emission centered at 575 nm disappeared after thermal annealing treatment in oxygen atmosphere. (C) 2007 Elsevier B.V. All rights reserved.