Browsing by Author "Huang, Hung-Wen"

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Double Photonic Quasi-Crystal Structure Effect on GaN-Based Vertical-Injection Light-Emitting Diodes
(2010)
Huang, Hung-Wen
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Lin, Chung-Hsiang
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Huang, Zhi-Kai
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Lee, Kang-Yuan
;
Yu, Chang-Chin
GaN-based thin-film vertical-injection light-emitting diodes (VLEDs) with a double 12-fold photonic quasi-crystal (PQC) structure formed using nanoimprint lithography (NIL) and inductively coupled plasma reactive-ion etching (ICP-RIE) are fabricated and presented. At a driving current of 20 mA and with a chip size of 350 x 350 mu m(2), our thin-film LED with a double-12-fold-PQC structure gave a light output power of 40.5 mW, which is an increase of 77% when compared with the output power of a VLED without a PQC structure at a peak wavelength of 460 nm. In addition, the corresponding light radiation patterns show a narrow beam shape due to the strong guided light extraction on the n-GaN surface and the reflected light effect of the PQC structure formed in the vertical direction on the p-GaN surface. (C) 2010 The Japan Society of Applied Physics
Efficiency enhancement of GaN-based power-chip LEDs with sidewall roughness by natural lithography
(2007)
Huang, Hung-Wen
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Lai, C. F.
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Wang, W. C.
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Lu, T. C.
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Kuo, H. C.
This study reports the development of GaN-based power-chip light-emitting diodes (LEDs) with sidewall roughness using natural lithography with polystyrene spheres as the etching mask. At an injection current of 350 mA, the LED with sidewall roughness increased the light output intensity of the InGaN/GaN multiple quantum well LEDs by a factor of 1.26, indicating that the LED with sidewall roughness had larger light extraction efficiency. The wall-plug efficiency of GaN-based LED was increased by 26.5% with sidewall roughness. After 1000 h life test, it was found that normalized output power of power-chip LED with sidewall roughness did not show any significant degradation. (c) 2006 The Electrochemical Society.
Enhanced Light Extraction Efficiency of GaN-Based Hybrid Nanorods Light-Emitting Diodes
(2015-07-01)
Huang, Jhih-Kai
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Liu, Che-Yu
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Chen, Tzi-Pei
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Huang, Hung-Wen
;
Lai, Fang-I
High light extraction GaN-based light-emitting diodes (LEDs) with a hybrid structure of straight nanorods located in an array of microholes have been successfully demonstrated. Via the nanoimprint lithography and photolithography techniques, high aspect-ratio light-guiding InGaN/GaN nanorods can be fabricated and regularly arranged in microholes, resulting in a great improvement of the light extraction for the GaN-based LED device. The light output power of the hybrid nanorods LED is 22.04 mW at the driving current standard of 25.4 A/cm(2), an enhancement of 38.7% to the conventional GaN-based LEDs. Furthermore, with a modification of the hybrid structures\' dimensions and locations, the emitted optical energy can be redistributed to obtain light-emitting devices with homogenueous optical field distributions.
GaN-based high-Q vertical-cavity light-emitting diodes
(2007-10-01)
Lu, Tien-Chang
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Kao, Tsung-Ting
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Kao, Chih-Chiang
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Chu, Jung-Tang
;
Yeh, Kang-Fan
We report a fabrication and demonstration of a GaN-based high-Q vertical-cavity light-emitting diode (VCLED). The GaN VCLED is composed of a 25-pair high-reflectivity (98%) GaN/AlN distributed Bragg reflector (DBR), an eight-pair SiO2/Ta2O5 dielectric DBR (99%), and a three-A optical thickness InGaN/GaN active region. It shows a very narrow linewidth of 0.52 nm, corresponding to a cavity Q-value of 895 at a driving current of 10 mA and a dominant emission peak wavelength at 465.3 nm. In addition, this VCLED emission linewidth continues to decrease with an increasing injection current, suggesting a possible realization of GaN-based vertical-cavity surface emitting lasers.
High extraction efficiency GaN-based light-emitting diodes on embedded SiO(2) nanorod array and nanoscale patterned sapphire substrate
(2010-06-28)
Huang, Hung-Wen
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Huang, Jhi-Kai
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Kuo, Shou-Yi
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Lee, Kang-Yuan
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Kuo, Hao-Chung
In this paper, GaN-based LEDs with a nanoscale patterned sapphire substrate (NPSS) and a SiO(2) photonic quasicrystal (PQC) structure on an n-GaN layer using nanoimprint lithography are fabricated and investigated. The light output power of LED with a NPSS and a SiO(2) PQC structure on an n-GaN layer was 48% greater than that of conventional LED. Strong enhancement in output power is attributed to better epitaxial quality and higher reflectance resulted from NPSS and PQC structures. Transmission electron microscopy images reveal that threading dislocations are blocked or bended in the vicinities of NPSS layer. These results provide promising potential to increase output power for commercial light emitting devices. (C) 2010 American Institute of Physics. [doi:10.1063/1.3456385]
High extraction efficiency GaN-based light-emitting diodes on embedded SiO2 nanorod array and nanoscale patterned sapphire substrate
(2010-06-28)
Huang, Hung-Wen
;
Huang, Jhi-Kai
;
Kuo, Shou-Yi
;
Lee, Kang-Yuan
;
Kuo, Hao-Chung
In this paper, GaN-based LEDs with a nanoscale patterned sapphire substrate (NPSS) and a SiO2 photonic quasicrystal (PQC) structure on an n-GaN layer using nanoimprint lithography are fabricated and investigated. The light output power of LED with a NPSS and a SiO2 PQC structure on an n-GaN layer was 48% greater than that of conventional LED. Strong enhancement in output power is attributed to better epitaxial quality and higher reflectance resulted from NPSS and PQC structures. Transmission electron microscopy images reveal that threading dislocations are blocked or bended in the vicinities of NPSS layer. These results provide promising potential to increase output power for commercial light emitting devices. (C) 2010 American Institute of Physics. [doi:10.1063/1.3456385]
Highly Efficient Light Extraction GaN-based Light Emitting Diode with Nano-rods in Micro-holes Compound Structure
(2014)
Liu, Che-Yu
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Huang, Jhih-Kai
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Lin, Da-Wei
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Huang, Hung-Wen
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Lee, Po-Tsung
We demonstrated a high-power GaN-based light emitting diodes (LEDs) which have micro-hole array and nano-rods compound structure by nanoimprint lithography (NIL). The nanorods structure inside the micro-hole could efficiently guide the trapped light from the GaN epilayer. Therefore, the light output power of LED with micro-hole array and nanorods was as high as 1.27 times, as compared with standard LED.
Improved Light Output Power of GaN-Based Light-Emitting Diodes Using Double Photonic Quasi-Crystal Patterns
(2009-11-01)
Huang, Hung-Wen
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Lin, Chung-Hsiang
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Huang, Zhi-Kai
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Lee, Kang-Yuan
;
Yu, Chang-Chin
The enhancement of light extraction from GaN-based light-emitting diodes (LEDs) with a double 12-fold photonic quasi-crystal (PQC) structure using nanoimprint lithography is presented. At a driving current of 20 mA on a transistor-outline-can package, the light output power of an LED with a nanohole patterned sapphire substrate (NHPSS) and an LED with a double PQC structure are enhanced by 34% and 61%, compared with the conventional LED. In addition, the higher output power of the LED with the double PQC structure is due to better reflectance on NHPSS and higher scattering effect on p-GaN surface using a 12-fold PQC structure pattern. These results provide promising potential to increase the output powers of commercial light-emitting devices.
Improvement of InGaN/GaN light emitting diode performance with a nano-roughened p-GaN surface by excimer laser-irradiation
(2006-10-10)
Huang, Hung-Wen
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Kao, C. C.
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Chu, J. T.
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Liang, W. D.
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Kuo, H. C.
In this paper, we reported the InGaN/GaN light emitting diode (LED) with a nano-roughened top p-GaN surface which caused by KrF excimer laser-irradiation. Comparing with the conventional LED, the brightness of InGaN/GaN light emitting diode (LED) was raised by a factor of 1.25 at 20 mA after KrF excimer laser-irradiation (250 mJ cm(-2) at 248 nm for 25 ns). Meanwhile, the operation voltage of InGaN/GaN LED was reduced from 3.55 to 3.3 V at 20 mA with 29% reduction in the series resistance. The causes for the brightness increase can be attributed to laser-irradiation induced nano-roughening of p-GaN surface. The reduction in the series resistance can be attributed to the increased contact area of nano-roughened surface and higher hole concentration after laser-irradiation. (c) 2005 Published by Elsevier B.V.
Investigation of InGaN/GaN light emitting diodes with nano-roughened surface by excimer laser etching method
(2007-01-25)
Huang, Hung-Wen
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Kao, Chih-Chiang
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Chu, Jung-Tang
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Wang, Wei-Chih
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Lu, Tien-Chang
The InGaN/GaN light emitting diodes (LEDs) with a nano-roughened top p-GaN surface fabricated by using Ni nano-masks and laser etching methods were demonstrated and analyzed. The experiment results observed the maximum light output power of the InGaN/GaN LED with a nano-roughened top p-GaN surface etched with the laser energy of 300 mJ/cm(2) was 1.55 times higher than that of a conventional LED, and the wall-plug efficiency was enhanced 68% at 20 mA. The series resistance of InGaN/GaN LED was reduced by 32% by the increase in the contact area of the nano-roughened surface. (c) 2006 Elsevier B.V. All rights reserved.
Metal organic chemical vapor deposition growth of GaN-based light emitting diodes with naturally formed nano pyramids
(2008-04-01)
Chiu, Ching-Hua
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Lee, Chia-En
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Lo, Ming-Hua
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Huang, Hung-Wen
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Lu, Tien-Chang
GaN-based light-emitting diodes (LEDs) with naturally formed nano pyramids roughened surfaces grown by metal organic chemical vapor deposition (MOCVD) were demonstrated. In this study, Mg-treatment, a growth-.interruption step and a surface treatment using biscyclopentadienyl magnesium (CP(2)Mg), was performed to form the nano pyramids on the surface of a p-type cladding layer, and then a p-type contact layer was grown on the p-type cladding layer, so as to create a p-type contact layer with a rough surface. Assisted by the nano pyramids surface roughening process, the light output power of the LEDs reached 11.3 and 9.7 mW with 10 and 5 min Mg-treatment at a driving current of 20 mA. The light outputs were increased by 48 and 27%, respectively, compared with the results from the LED without Mg-treatment.
Method for promoting light emission efficiency of LED using nanorods structure
(2008-12-11)
Huang, Hung-Wen
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Lu, Tien-Chang
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Chiu, Ching-Hua
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Kuo, Hao-Chung
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Wang, Shing-Chung
Method for the light emitting diode (LED) having the nanorods-like structure is provided. The LED employs the nanorods are subsequently formed in a longitudinal direction by the etching method and the PEC method. In addition, the plurality of the nanorods is arranged in an array so that provide the LED having much greater brightness and higher light emission efficiency than the conventional LED.
On Closing the Gap Between Pre-simulation and Post-simulation Results in Nanometer Analog Layouts
(2018-01-01)
Pan, Po-Cheng
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Huang, Hung-Wen
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Huang, Chien-Chia
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Patyal, Abhishek
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Chen, Hung-Ming
In order to generate analog layout in advanced technology, it still remains lots of challenges due to the imprecise estimation of critical performance parameters. We propose an upgraded decision making framework, PEDefer, to decompose existing layout into decisive components for performance estimation. In this work, the objective is to synthesize layout solutions based on the performance estimation of user-defined constraints and existing templates. The constraints of the circuit are priorly tackled in the partition and layout enumeration stage. In addition, we attempt to have partial layout pieces as exchangeable blocks to perform pseudo-post-simulation, thus to put simulation factors in the evaluation during layout enumeration strategy. The experiments show that this flow guarantees valid analog layout results whose performances are closer to netlist-level simulation than manual designed or migrated layouts with minimal overhead.