Browsing by Author "Chang, C. H."

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A new series resistance and mobility extraction method by BSIM model for nano-scale MOSFETs
(2006)
Chen, William P. N.
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Su, P.
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Wang, J. S.
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Lien, C. H.
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Chang, C. H.
Biomimetic Antireflection Coating for Efficiency Enhancement of Triple-Junction Solar Cells Utilizing Nanosphere Lithography
(2010)
Chiu, M. Y.
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Chang, F. Y.
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Chang, C. H.
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Tsai, M. A.
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Yu, Peichen
In this work, we demonstrate a thorough device design, fabrication, characterization, and analysis of biomimetic antireflective structures implemented on a Ga(0.5)In(0.5)P/GaAs/Ge triple-junction solar cell. The sub-wavelength structures are fabricated on a silicon nitride passivation layer using polystyrene nanosphere lithography followed by anisotropic etching. Both the reflectance spectroscopy and external quantum efficiency measurements confirm the improved optical absorption in the ultraviolet/blue and near-infrared wavelengths. Hence, the conversion efficiency of cell with sub-wavelength structure (SWS) is enhanced by 46.1% and 3.4% due to much improved current-matching, compare to cells without an ARC and SL ARC, respectively. We further employ RCWA method to analyze the reflectance by tuning structural factors such as periodicity or height of the SWS.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nano-columns prepared by glancing-angle deposition with nitrogen (vol 94, 051114, 2009)
(2013-11-11)
Chang, C. H.
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Yu, P.
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Yang, C. S.
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光電工程學系
;
Department of Photonics
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
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Yang, C. S.
;
光電工程學系
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Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen (Retracted article. See vol. 104, 269901, 2014)
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen (Retracted article. See vol. 104, 269901, 2014)
(2009-02-02)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Characteristic formation of highly oriented indium-tin-oxide (ITO) nanocolumns is demonstrated using electron-beam evaporation with an obliquely incident nitrogen flux. The nanocolumn material exhibits broadband and omnidirectional antireflective characteristics up to an incidence angle of 70 degrees for the 350-900 nm wavelength range for both s- and p-polarizations. Calculations based on a rigorous coupled-wave analysis indicate that the superior antireflection arises from the tapered column profiles which collectively function as a gradient-index layer. Since the nanocolumns have a preferential growth direction which follows the incident vapor flux, the azimuthal and polarization dependence of reflectivities are also investigated. The single ITO nanocolumn layer can function as antireflection contacts for light emitting diodes and solar cells.
Broadband and omnidirectional antireflection from conductive indium-tin-oxide nanocolumns prepared by glancing-angle deposition with nitrogen (Retraction of vol 94, 051114, 2009)
(2014-06-30)
Chang, C. H.
;
Yu, Peichen
;
Yang, C. S.
;
光電工程學系
;
Department of Photonics
Comparing the performances of Pentacene based TFTs use MWCNTs and Pd/Ti as source and drain
(2007)
Chang, C. H.
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Chien, C. H.
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Yang, J. 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
Design Improvement of a Staggered YBCO Undulator
(2018-04-01)
Chen, S. D.
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Chiang, C. A.
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Yang, C. M.
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Yang, C. K.
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Luo, H. W.
A strong field and short period undulator can be a desirable light source device in a storage ring or a free-electron laser. Bulk YBCO can be used to construct a high-temperature-superconducting undulator in a staggered array structure. The YBCO material in form of 32 mm diameter and 2.5 mm thick was used to assemble a staggered magnet array. The period length is 5 mm and the magnet gap is 4 mm. To estimate the strength of a sinusoidal field and to optimize the end-pole design to minimize the first (i.e., electron angle) and second field integral (electron position), an energy-minimization method (EM-method) based on Bean's model to simulate the field trapped in the HTS-Block is introduced. In this paper, we focus on promoting the practical value of the EM-method simulation. Combining the experimental experience of a YBCO staggered undulator and the simulation experience based on the EM-method, we address some issues to enhance the efficacy of this undulator design.
Design of a Hybrid Multiperiod Robinson Wiggler for TPS Light Source
(2016-06)
Huang, C. W.
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Chung, T. Y.
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Chang, C. H.
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Hwang, C. S.
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電子物理學系
A Robinson wiggler is designed to decrease the emittance within 1 nm . rad for Taiwan Photon Source. According to an analysis of the beam dynamics, decreasing the emittance with a multiperiod Robinson wiggler is more efficient than a single-period traditional Robinson wiggler. This wiggler consists of a dipole field and a strong gradient field, which creates a strong dynamic field integral multipole error. To enhance the gradient field and to have also a small dynamic field integral multipole error, a compensated side-pole design and an edge-pole shape in each pole are proposed in this paper. After optimization of the magnet, the dipole and gradient fields are 0.82 T and -37 T/m, respectively. The concept of the design of the magnetic circuit and the results of an analysis of the magnetic field are discussed herein.
Development of rapid and ultrasensitive flexible palladium nano-thin film biosensing electrode for V. Orientalis detection
(2018-12-01)
Wu, C. H.
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Huang, Y. Z.
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Chang, C. Y.
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Chang, C. H.
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生物科技學系
Development trends for insertion devices of future synchrotron light sources
(2011-04-28)
Hwang, C. S.
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Jan, J. C.
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Chang, C. S.
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Chen, S. D.
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Chang, C. H.
The in-vacuum undulator with a permanent magnet at room temperature is a mature technology and is widely used; with a short period length in a medium-energy facility, it can enhance photon brilliance in the hard x-ray region. A cryogenic permanent magnet has been investigated as an in-vacuum undulator; this undulator will become the best prospective device to satisfy the requirements of a photon source with great brilliance in the hard x-ray region. For the further hard x-ray region, a superconducting wiggler can provide great flux with a continuous spectrum, whereas a superconducting undulator will provide great brilliance with a discrete spectrum. High-temperature superconducting wires are highly promising for use in the development of superconducting undulators; unique algorithms for their development with an extremely short period in a small-magnet gap have been devised. Some out-of-vacuum planar undulators with special functions must also be fabricated to enable diverse applications in various light-source facilities. This article describes current and future developments for insertion devices in storage-ring and free-electron-laser facilities and discusses their feasibility for use therein.
Effect of Stony Debris Flow on Design Discharge for Tung-Pu-Ray Creek
(2004)
Hsieh, T. Y.
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Chang, C. H.
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Pen, S. C.
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Yang, J. C.
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防災與水環境研究中心
The primary objective of this research is to investigate the impact of stony debris flows of Tung-Pu-Ray Creek on its design discharge by using the quasi two-dimensional cell model for inundation simulation. The research is based on the assumption that there is a linear relationship between the actual discharge hydrograph of sediment-laden flows, and the discharge hydrograph of sediment free flows. That is, the ordinates of the discharge hydrograph of sediment-laden flows are n times of water flows. Hence, using the inundation simulation by the quasi two-dimensional cell model, one can define the extent of the impact of stony debris flows of Tung-Pu-Ray Creek on its design discharge through the calibration with the actual flood inundation of the typhoon Toraji of 1990. The simulation indicates that the actual discharge of Tung-Pu-Ray Creek's sediment flows can be determined as 1.4 times of the discharge hydrograph derived from the actual precipitation data. In other words, the weighted impact of the stony debris flows on the design discharge is approximately 0.4 times in the Tung-Pu-Ray Creek case.
Efficiency Enhancement of GaN/InGaN Vertical-Injection Light Emitting Diodes Using Distinctive Indium-Tin-Oxide Nanorods
(2009)
Yang, C. S.
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Yu, Peichen
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Chiu, C. H.
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Chang, C. H.
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Kuo, H. C.
Distinctive indium-tin-oxide nanorods are demonstrated using glancing-angle deposition. The nanostructured material exhibit enhanced transmission and is employed to enhance the light-output-power of GaN/InGaN vertical-injection light emitting diodes by 20% at an injection current of 350mA. (C) 2008 Optical Society of America
ENHANCED ANGULAR RESPONSE OF POWER CONVERSION EFFICIENCY FOR SILICON SOLAR CELLS UTILIZING A UNIFORMLY DISTRIBUTED NANO-WHISKER MEDIUM
(2010)
Chang, C. H.
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Hsu, M. H.
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Chang, W. L.
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Sun, W. C.
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Wu, C. W.
In the research of photovoltaic devices, eliminating Fresnel reflection loss is a critical issue on the way to pursue higher efficiency. To maximize the power conversion efficiency, dielectric anti reflective coating shows a cost-effective approach, but not enough to absorb broadband solar radiation effectively. Recently, the functional nanostructure shows high potential to be an omnidirectional anti reflective coating for the photovoltaic devices. Here we demonstrate Indium-Tin-Oxide (ITO) nano-whiskers, grown by the self-catalyst vapor-liquid-solid (VLS) mechanisms on the textured Si substrate. The ITO nano-whiskers can provide broadband anti-reflective properties (R < 5%) in the wavelength range of 350-1100nm. In comparison with conventional Si solar cell, the ITO nano-whiskers coating solar cell shows higher external quantum efficiency (EQE) in the range of 700-1100nm. Moreover, the ITO nano-whisker coating Si solar cell shows a high total efficiency increase of 1.1% (from 16.08% to 17.18%). The angular response of the conversion efficiency also increases from 7% at the normal incidence to more than 15% for incident angles over 70 degrees.
HIGH EFFICIENCY GALLIUM ARSENIDE SOLAR CELLS USING INDIUM-TIN-OXIDE NANO-COLUMNS
(2008)
Chang, C. H.
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Yu, Peichen
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Chiu, C. H.
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Kuo, H. C.
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光電工程學系
An array of conductive Indium-Tin-Oxide (ITO) nano-columns is deposited on GaAs solar cells using the oblique-angle electron-beam deposition method. Calculations based on a rigorous coupled-wave analysis method show that such ITO nano-columns offer superior angular and spectral anti-reflective (AR) properties. The optical characteristics of the ITO nano-columns are described. The conversion efficiency of GaAs solar cells with ITO nano-columns as the AR coating is increased by 23%, mainly limited by the quantum efficiency at the wavelengths below 600nm.
Indium-Tin-Oxide Nanowhiskers Crystalline Silicon Photovoltaics Combining Micro- and Nano-Scale Surface Textures
(2011)
Chang, C. H.
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Hsu, M. H.
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Chang, W. L.
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Sun, W. C.
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Yu, Peichen
In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The combined surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on passivated, micro-grooved silicon solar cells using electron-beam evaporation. The nanowhiskers facilitate optical transmission in the near-infrared, which is optically equivalent to a stack of two dielectric thin-films with step- and graded- refractive index profiles. The ITO nanowhiskers provide broadband anti-reflective properties (R < 5%) in the wavelength range of 350-1100nm. In comparison with conventional Si solar cell, the combined surface texture solar cell shows higher external quantum efficiency (EQE) in the range of 700-1100nm. Moreover, the ITO nanowhisker coating Si solar cell shows a high total efficiency increase of 1.1% (from 16.08% to17.18%). Furthermore, the nanowhiskers also provide strong forward scattering for ultraviolet and visible light, favorable in thin-wafer silicon photovoltaics to increase the optical absorption path.
Influence of Passivation Layers on Characteristics of High Mobility Amorphous Indium-Zinc-Tin-Oxide Thin-Film Transistors
(2016-01-01)
Liu, P. T.
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Chang, C. H.
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Zheng, G. T.
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Chang, C. C.
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電子工程學系及電子研究所
We investigated the influence of passivation-layer deposition on the characteristics of a-InZnSnO thin-film transistors (TFTs). The threshold voltage (Vth) of the TFTs shifted markedly as a result of the ion bombardment induced by the passivation layers above. By adjusting the post annealing temperature, the performance of the TFTs can be modulated. The a-InZnSnO TFTs after passivation exhibited good performance with a field-effect mobility of 21.34 cm(2)/Vs, a threshold voltage of -5.03V, and a subthreshold slope of 0.52 V/decade.
Novel Indium-Tin-Oxide Nano-Whiskers for Enhanced Transmission of Surface-Textured Silicon Photovoltaic Cells
(2009)
Chang, C. H.
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Hsu, Min-Hsiang
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Yu, Peichen
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Kuo, H. C.
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Chang, W. L.
Conductive Indium-Tin-Oxide (ITO) nano-whiskers were deposited on surface-textured Si solar cells using glancing-angle electron-beam deposition. With different deposited time, the ITO nano-structured layer exhibit tunable thickness, which can be related to the surface reflectance. The optimized nano-whisker surface demonstrates a broadband anti-reflective properties (R<5%), better than the traditional Si(3)N(4) antireflection coating. Current-voltage and quantum efficiency analyses with the measured reflectivity data show enhanced optical transmission in the long wavelength range from 700nm to 1000nm, corresponding to a conversion efficiency improvement from 13.93% to 14.37%.
Oblique electron-beam evaporation of distinctive indium-tin-oxide nanorods for enhanced light extraction from InGaN/GaN light emitting diodes
(2009-11-09)
Chiu, C. H.
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Yu, Peichen
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Chang, C. H.
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Yang, C. S.
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Hsu, M. H.
This paper presents a novel and mass-producible technique to fabricate indium-tin-oxide (ITO) nanorods which serve as an omnidirectional transparent conductive layer (TCL) for InGaN/GaN light emitting diodes (LEDs). The characteristic nanorods, prepared by oblique electron-beam evaporation in a nitrogen ambient, demonstrate high optical transmittance (T>90%) for the wavelength range of 450nm to 900nm. The light output power of a packaged InGaN/GaN LED with the incorporated nanorod layer is increased by 35.1% at an injection current of 350mA, compared to that of a conventional LED. Calculations based on a finite difference time domain (FDTD) method suggest that the extraction enhancement factor can be further improved by increasing the thickness of the nanorod layer, indicating great potential to enhance the luminous intensity of solid-state lighting devices using ITO nanorod structures. (C) 2009 Optical Society of America