Browsing by Author "Tsai, Y. L."

Now showing 1 - 12 of 12

A HIGHLY EFFICIENT HYBRID CDS-GAAS SOLAR CELL
(2012)
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Han, H. V.
;
Yu, Peichen
A novel design of hybrid solar cell combining traditional GaAs-based solar cell with colloidal CdS quantum dots (ODs) is demonstrated. By applying CdS ODs on the surface of GaAs device, we can obtain an effective antireflection coating at long wavelength. Moreover, due to its strong absorption at ultraviolet range and efficient light emission at blue photon, CdS quantum dots can down-convert the high-energy UV photons into visible ones, which are more easily to be collected in GaAs solar cell. The short circuit current and power conversion efficiency of this new device increases by 21% and 18.9%, respectively, when we compare them to the uncoated GaAs solar cell. An increase of the surface photoconductivity was also detected due to UV presence, and the fill factor of the CdS ODs solar cell can be improved accordingly.
A Novel Monopulse Antenna Using an Artificial Magnetic Conductor in Metallic Corner Reflectors
(2015)
Tsai, Y. L.
;
Hwang, R. B.
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A monopulse antenna composed of corner reflectors was designed, fabricated, and measured. The antenna consists of two corner reflector antennas: the first is used for the sum pattern and the second is used for the difference pattern. The corner reflectors for the sum pattern antenna are made of two sheets of metallic plates arranged orthogonally to each other. Replacing one sheet of the corner reflector of the sum antenna with an artificial magnetic conductor (AMC) sheet transforms it into an antenna for the difference pattern. This proposed antenna design realizes a monopulse antenna system that does not require a complex multiple mode excitation network and phasing circuitry. The experimental results reveal that the peak gain of the difference antenna was 10.6 dBi, the null depth of the difference antenna was lower than -25 dB, the field of view was approximately 22 degrees, and the side lobe level was approximately -13 dB at 2.6 GHz. With the achieved specifications, this antenna system has considerable potential in target localization and angle tracking applications.
Design of Highly Absorption Structure by Flatted ITO Patterned Substrate for Thin Film a-Si Solar Cells
(2012)
Han, H. V.
;
Shih, H. S.
;
Chen, H. C.
;
Tsai, Y. L.
;
Yu, P. C.
The patterned substrate is a flatted structure which composed with two materials to enhance the absorption of a-Si solar cell. We optimized this structure by simulation method and find it has good omnidirectional antireflection effect. (C) 2012 Optical Society of America
EFFICIENCY ENHANCEMENT IN SINGLE JUNCTION INGAP SOLAR CELLS BY USING SELF-ASSEMBLED NANOSPHERES
(2010)
Chen, H. C.
;
Tsai, Y. L.
;
Wang, H. W.
;
Tsai, M. A.
;
Tseng, P. C.
A single-junction InGaP solar cells with polystyrene (PS) nanospheres on the surface has been developed. The self-assembly of PS nanospheres is one of the simplest and the fastest methods with which to build a 20 closely packed periodic structure. Based on the scattering of the PS nanospheres, the light path length can be increased. As compared to the InGaP solar cells without PS nanospheres on the top surface the standard process. An increase short-circuit current form 8.93% to 10.31% is improved when a single-junction InGaP solar cells with PS nanospheres. The conversion efficiency measured can also be improved from 8.79% to 9.71%. The single-junction InGaP solar cell with PS nanospheres was achieved.
Efficiency Enhancement in Single-Junction InGaP Solar Cells by Using Self-Assembled Nanospheres
(2011-06-01)
Chen, H. C.
;
Lin, C. C.
;
Wang, H. W.
;
Tsai, M. A.
;
Tseng, P. C.
A single-junction InGaP solar cell with polystyrene (PS) nanospheres on the surface has been developed. The self-assembly of PS nanospheres is one of the simplest and the fastest methods with which to build a 2-D closely packed periodic structure. Due to the scattering of the PS nanospheres, the light path length can be increased when compared to the InGaP solar cells without PS nanospheres on the top. An increase short-circuit current from 8.93 to 10.31 mA is improved when a single-junction InGaP solar cell is coated with PS nanospheres. The conversion efficiency measured can also be improved from 8.79% to 9.71%. The single-junction InGaP solar cell with PS nanospheres was achieved.
EFFICIENCY ENHANCEMENT InGaP/GaAs DUAL-JUNCTION SOLAR CELL WITH SUB-WAVELENGTH ANTIREFLECTION NANOROD ARRAYS
(2010)
Wang, H. W.
;
Tsai, M. A.
;
Chen, H. C.
;
Tsai, Y. L.
;
Tseng, P. C.
The enhanced conversion efficiency of the InGaP/GaAs dual-junction solar cell was demonstrated antireflection nanorod arrays. After self-assembled Ni clusters, the nanorod arrays were fabricated by inductively-coupled-plasma reactive ion etching. The conversion efficiency were measured under one-sun air mass 1.5 global illuminations at room temperature. The short current of the nanorod arrays cell was enhanced 10.0% and the efficiency was enhanced 10.8%. We were also studied the light absorption efficiencies of the top InGaP and bottom GaAs cells under the influence of nanorod arrays. Surface nanorod arrays were not only as antireflection layers but also scattering sources. The nanorod arrays structure can be significant improved the maximum conversion efficiency.
Enhance current density and light trapping effect in a-Si thin film solar cells by flexible textured PDMS film
(2013)
Han, H. V.
;
Chen, H. C.
;
Tsai, Y. L.
;
Lin, C. C.
;
Kuo, H. C.
The light trapping effect of a textured polydimethylsiloxane (PDMS) film on the suppression of surface reflection in a-Si:H solar cell is investigated. The angular dependence of scattered light from this PDMS film was measured and a symmetric scattering intensity peak was found at +/- 20(0). The enhancement of power conversion efficiency in the a-Si:H solar cell with textured PDMS film can reach 16.37% compared to the a-Si:H solar cells without textured PDMS film. This improvement is mainly attributed to the enhanced efficiencies of light trapping and scattering. Such a design concept and fabrication process can be widely adapted to a variety of thin film solar cells.
Enhancement of Light Harvesting and Power Conversion Efficiency in GaAs solar cells using flexible textured PDMS film
(2013-01-01)
Han, H. V.
;
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Yeh, Y. L.
Light trapping of textured polydimethylsiloxane films for antireflection is investigated. The efficiency of GaAs solar cell with textured PDMS film reach 28% enhancement. Numerical analysis successfully rebuilds the surface profile close to the real situation. (C) 2013 Optical Society of America
Improve GaAs Solar Cells Efficiency by Using High-transmittance Textured PDMS Film
(2013)
Han, H. V.
;
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Kuo, H. C.
We demonstrate the GaAs solar cells which utilize the high-transmittance textured polydimethylsiloxane (PDMS) film can outstanding increase the short circuit current density and power conversion efficiency of solar cells. The transmittance of PDMS film is exceeded 90%, which can pass through almost all the light of GaAs Solar cells can be absorbed. We used a special imprint technology to let the PDMS film possess a highly textured surface. Then we measured the characteristics of textured PDMS film and found out that it has a very excellent Haze performance. The effect of flexible textured PDMS film on the suppression of surface reflection in GaAs solar cells is also investigated. The presented technology provides an inexpensive surface anti-reflection process, which can potentially replace typically complex anti-reflection coating (ARC) layer. The GaAs solar cells with textured PDMS layer can effectively enhance the short-circuit current density from 22.91 to 26.54 mA/cm(2) and the power conversion efficiency from 18.28 to 21.43 %, corresponding to a 17 % enhancement compared to the one without textured PDMS. The open-circuit voltage (V-oc) and the fill-factor (FF) of GaAs solar cells exhibit negligible change, because the textured PDMS film was pasted up on the surface of GaAs solar cells and did not interfere with the diode operation. At the same time, we observed through the EQE measurement that the textured PDMS film not only proved wonderful light scattering effect but also generated more electron-hole pairs in all absorption spectrum range. Finally, through this simple PDMS process, we believe this technology shall be a great candidate for next generation of highly efficient and low-cost photovoltaic devices.
LARGE-SCALE AND ENHANCED EFFICIENCY C-SI SOLAR CELL WITH MOTH-EYE-LIKE BY USING SELF-ASSEMBLED LITHOGRAPHY
(2010)
Tsai, M. A.
;
Chen, H. C.
;
Wang, H. W.
;
Tsai, Y. L.
;
Tseng, P. C.
We demonstrated the Si solar cell with ladder-shaped nanorod array, fabricated by combined the self-assembled lithography and reactive-ion etching technique. The measurement of angular reflective spectrums of the solar cell with ladder-shaped nanorod array using an integration sphere remained lower at broadband spectra and large angle of incident compared to the solar cell with micro-textured surface. The I-V measurement shown the current density and conversion efficiency could be improved by the ladder-shaped nanorod array. The enhancement conversion efficiency approached to 34.54%.
The Understanding of Multi-level RTN in Trigate MOSFETs Through the 2D Profiling of Traps and Its Impact on SRAM Performance: A New Failure Mechanism Found
(2012)
Hsieh, E. R.
;
Tsai, Y. L.
;
Chung, Steve S.
;
Tsai, C. H.
;
Huang, R. M.
The impact of multi-level RTN on SRAM cells bas been experimentally demonstrated on both planar and trigate CMOS devices. First, to study multi-level RTN, a simple experimental method has been developed to take the 2D profiling of multi-traps in both oxide depth (vertical) and channel(lateral) directions in the gate oxide. Then, the role of traps in the switching mechanisms of SRAM cells has also been examined. Results show that the multi-traps will degrade RSNM (read static noise margin), as well as cause transition failure in SRAM operations. This is the first being observed and reported that will be considered as a major criterion in the future low voltage design of SRAM cells.
Welding overlay analysis of dissimilar metal weld cracking of feedwater nozzle
(2010-01-01)
Tsai, Y. L.
;
Wang, Li. H.
;
Fan, T. W.
;
Ranganath, Sam
;
Wang, C. K.
Inspection of the weld between the feedwater nozzle and the safe end at one Taiwan BWR showed axial indications in the Alloy 182 weld. The indication was sufficiently deep that continued operation could not be justified considering the crack growth for one cycle. A weld overlay was decided to implement for restoring the structural margin. This study reviews the cracking cases of feedwater nozzle welds in other nuclear plants, and reports the lesson learned in the engineering project of this weld overlay repair. The overlay design, the FCG calculation and the stress analysis by FEM are presented to confirm that the Code Case structural margins are met. The evaluations of the effect of weld shrinkage on the attached feedwater piping are also included. A number of challenges encountered in the engineering and analysis period are proposed for future study. (C) 2009 Elsevier Ltd. All rights reserved.