Browsing by Author "Huang, C. K."

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Biomimetic nanostructured antireflection coating and its application on crystalline silicon solar cells
(2011-07-18)
Chen, J. Y.
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Chang, W. -L.
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Huang, C. K.
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Sun, K. W.
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應用化學系
In this report, we demonstrate the implementation of biomimetic nanostructured antireflection coatings with polymethyl methacrylate (PMMA) layer on the micro-textured surface of silicon crystalline solar cells. To reduce cost, the process combines colloidal lithography, cast molding method, and reversal nanoimprint lithography. The technique is simple, low cost, and does not cause damage to the thin and brittle conventional crystalline solar cells. The antireflection properties of this biomimetic nanostructure coating are considered as effective as those of a conventional single-layer SiN(x) thin film. The resultant structures alone could reduce the average reflectance of solar cell from 13.2% to 7.8% and enhance power conversion efficiency from 12.85% to 14.2%. (C)2011 Optical Society of America
Development of a heat-generable mold insert and its application to the injection molding of microstructures
(2014-04-01)
Liou, A. C.
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Chen, R. H.
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Huang, C. K.
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Su, C. H.
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Tsai, P. Y.
This work presents a heat-generable mold insert for micro injection molding that solves the problem of de-molding destruction. This mold insert is constructed from silicon wafer by silicon micro-fabrication. Micro electrical heating lines were formed in the wall of the micro mold cavity to control the temperature distribution and the sequence of local solidification of the filled plastic during injection molding. This design reduces the shrinking stress of the plastic filled in the mold. The micro electrical heating lines embedded in the cavity wall are silicon-based with specified resistance, and were fabricated by doping phosphorus ions precisely into the surface of the silicon cavity wall. Ion-implantation was adopted to dope phosphorus ions. The performance of the novel mold insert was studied. Then, the developed mold insert was applied for the injection molding of micro-structures with high aspect ratios. Experimental results reveal that electrical heating lines formed within the novel mold insert can supply stable heating power. These electrical heating lines are used to heat the cavity wall of the silicon mold insert and the nearby plastic with appropriate timing at sufficient power in the cooling stage, such that the de-molding force associated with contraction of the patterned plastic grips to the micro-structured mold insert, is reduced. Furthermore the de-molding destruction of the injection molded micro-structures can be eliminated. Optical micro-structures with aspect ratios of up to eight were successfully injection-molded. (C) 2013 Elsevier B.V. All rights reserved.
Development of optimised carrier sequence in MCU-based random-frequency PWM
(2007-01-01)
Chen, H. C.
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Chang, Y. C.
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Huang, C. K.
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電控工程研究所
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Institute of Electrical and Control Engineering
The effect of the carrier sequences on the voltage spectrum of MCU(microcontroller)based random-frequency pulse-width modulation (RFPWM) is presented. To optimise the carrier sequence efficiently, first all possible sequences are classified into groups according to the time-shift and time-reverse properties of the Fourier transform. Then, some evaluation indexes are proposed to obtain the optimal sequence quickly with the end of a personal computer (PC). Finally, some optimised carrier sequences with only two carrier frequencies are recommended. The experimental results also indicate that we should pay more attentions to the carrier sequences than to the selection of carrier frequency and on the numbers of carrier frequencies.
Efficiency enhancement of silicon solar cells using a nano-scale honeycomb broadband anti-reflection structure
(2012-01-02)
Huang, C. K.
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Sun, K. W.
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Chang, W-L.
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應用化學系
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Department of Applied Chemistry
This experiment demonstrates the process for manufacturing a ZnO honeycomb sub-wavelength structure using nanosphere lithography technology exhibiting excellent anti-reflection properties from the UV to NIR wavelength regions. This honeycomb nanostructure, combined with commercially available crystalline Si solar cells, show substantially improved conversion efficiency from 15.6% to 16.6% using optimized honeycomb sizes and precursor concentrations of ZnO. The present work develops an unsophisticated and economical technique suitable for industrial applications in producing a uniform and low-reflective texture. (C)2011 Optical Society of America
Efficiency enhancement of the poly-silicon solar cell using self-assembled dielectric nanoparticles
(2011-08-01)
Huang, C. K.
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Lin, H. H.
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Chen, J. Y.
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Sun, K. W.
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Chang, W. -L.
In this study, silica nanospheres dispersed in a surfactant solution were spin-coated on commercially available silicon solar cells to form colloidal crystals on the surface. This self-assembled nanoparticle layer served as an anti-reflection (AR) layer for solar cell devices. The self-assembled layer exhibits excellent anti-reflection properties in the UV and NIR wavelength regions, and the reflectance spectra match the theoretical prediction done using the rigorous coupled-wave analysis model. We also showed that the overall conversion efficiency of polycrystalline Si solar cells coated with the silica nanospheres was increased from 11% to 12.3% when using optimized spin-coating parameters and nanoparticle concentrations. (C) 2011 Elsevier B.V. All rights reserved.
Efficiency improvement of Si solar cells using metal-enhanced nanophosphor fluorescence
(2014-01-01)
Chen, J. -Y.
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Huang, C. K.
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Hung, W. B.
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Sun, K. W.
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Chen, T. M.
In this study, Eu2+-doped barium silicate (Ba2SiO4:Eu2+) nanophosphors dispersed in a surfactant solution were spin-coated on commercially available silicon solar cells to form colloidal crystals on the surface. The crystals then act as luminescence down-shifting centers to generate low-energy photons for incident ultraviolet light. The fluorescence from the Ba2SiO4:Eu2+ nanophosphors was further enhanced by coating a metal-enhanced layer composed of Ag nanoparticles and a SiO2 spacer. The solar cells showed an enhancement of 0.86 mA/cm(2) in short-circuit current density and approximately 0.64% increase in power conversion efficiency when coated with nanophosphors, SiO2 spacers, and Ag nanoparticles. The properties of cells integrated with the metal-enhanced layer were characterized to identify the roles of nanophosphors and Ag nanoparticles in improved light harvesting. These experiments demonstrated that the colloids of Ba2SiO4:Eu2+ acted as luminescence down-shifting centers in the ultraviolet region and the metallic nanoparticles also helped to enhance fluorescence in the visible region to increase light absorption within the measured spectral regime. (C) 2013 Elsevier B.V. All rights reserved.
Enhanced light harvesting of Si solar cells via luminescent down-shifting using YVO4:Bi3+, Eu3+ nanophosphors
(2013-11-01)
Huang, C. K.
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Chen, Y. C.
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Hung, W. B.
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Chen, T. M.
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Sun, K. W.
The colloids of YVO4 nanoparticles on microtextured Si surface are demonstrated to have promising potential for efficient solar spectrum utilization in crystalline Si solar cells. The solar cells showed an enhancement of 4% in short-circuit current density and approximately 0.7% in power conversion efficiency when coated with YVO4 nanoparticles. The properties of cells integrated with YVO4 nanoparticles were characterized to identify the role of YVO4 in improved light harvesting. The current experiments conclude that the colloids of YVO4 nanoparticles not only act as luminescent down-shifting centers in the ultraviolet region but also serve as an antireflection coating for enhancing the light absorption in the measured spectral regime. Copyright (c) 2012 John Wiley & Sons, Ltd.
GaN MIS-HEMT with Low Dynamic ON-resistance Using SiON Passivation
(2016-01-01)
Liu, S. C.
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Huang, C. K.
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Chang, E. Y.
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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
An effective SiON passivation with high density of positive fixed charges for GaN MIS-HEMTs is demonstrated. The positive fixed charges at the SiON/AlGaN interface effectively reduce the surface potential and expand the quantum well below the Fermi level, thus improving the device performance. The GaN MIS-HEMT with SiON demonstrated a high maximum drain-source current density (I-DS,I-max) of > 1 A/mm, a breakdown voltage of 750 V at a drain leakage current of 1 mu A/mm, and a well transfer characteristics. The dynamic ON-resistance only increased slightly under a high quiescent bias of 100 V.
Practical sensorless control for inverter-fed BDCM compressors
(2007-01-01)
Chen, H. C.
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Chang, Y. C.
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Huang, C. K.
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電控工程研究所
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Institute of Electrical and Control Engineering
Brushless DC motors (BDCMs) possess higher efficiencies than the conventional induction motors and BDCMs have therefore been used widely in inverter-fed compressors. Since the Hall position sensors cannot work well in the high-temperature environment of refrigerants, sensorless control schemes play an important role in the application of inverter-fed BDCM compressors. Sensorless control for actual BDCM compressor is proposed and implemented. First, the sensorless circuits used have been analysed in detail to find the design rules of the circuit parameters for various compressor motors. Then, the limitations of sensorless control are discussed to develop a practical speed controller for BDCM compressors. The developed starting strategy and sensorless algorithms are presented and digitally implemented. Finally, some experimental results are displayed to demonstrate the proposed sensorless speed control for BDCM compressors.