Browsing by Author "Lee, B. D."

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Enhanced light output from a nitride-based power chip of green light-emitting diodes with nano-rough surface using nanoimprint lithography
(2008-05-07)
Huang, H. W.
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Lin, C. H.
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Yu, C. C.
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Chiu, C. H.
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Lai, C. F.
Enhanced light extraction from a GaN-based power chip (PC) of green light-emitting diodes (LEDs) with a rough p-GaN surface using nanoimprint lithography is presented. At a driving current of 350 mA and with a chip size of 1 mm x 1 mm packaged on transistor outline (TO)-cans, the light output power of the green PC LEDs with nano-rough p-GaN surface is enhanced by 48% when compared with the same device without a rough p-GaN surface. In addition, by examining the radiation patterns, the green PC LED with nano-rough p-GaN surface shows stronger light extraction with a wider view angle. These results offer promising potential to enhance the light output powers of commercial light-emitting devices by using the technique of nanoimprint lithography under suitable nanopattern design.
Enhanced light output power of GaN-based vertical-injection light-emitting diodes with a 12-fold photonic quasi-crystal by nano-imprint lithography
(2009-08-12)
Huang, H. W.
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Lin, C. H.
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Lee, K. Y.
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Yu, C. C.
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Huang, J. K.
GaN-based thin-film vertical-injection light-emitting diodes (VLEDs) with a 12-fold photonic quasi-crystal (PQC) by nano-imprint lithography (NIL) are fabricated and presented. At a driving current of 20 mA and with a chip size of 350 mu m x 350 mu m, the light output power of our thin-film LED with a 12-fold PQC structure reaches 41 mW. This result is an enhancement of 78% when compared with the output power of a VLED without a PQC structure. In addition, the corresponding light radiation pattern shows a narrower beam shape due to the strong guided light extraction effect by the formed PQC structure in the vertical direction.
Improvement of light output in GaN-based power chip light-emitting diodes with a nano-rough surface by nanoimprint lithography
(2008-04-01)
Huang, H. W.
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Lin, C. H.
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Yu, C. C.
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Lee, B. D.
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Chiu, C. H.
The enhancement of light extraction of gallium nitride (GaN)-based power chip (PC) light-emitting diodes (LEDs) with a p-GaN rough surface by nanoimprint lithography (NIL) is presented. At a driving current of 350 mA and a chip size of 1 mm x 1 mm, the light output power of the PC LEDs with a p-GaN rough surface (etching depth from 130 to 150 nm) showed an enhancement of 24% on wafer when compared with the same device without NIL. Current-voltage results indicated an ohmic contact by the increase in the contact area of the nano-roughened surface at 200 mA. This paper offers a promising potential for enhancing the output powers of commercial LEDs.
Investigation of GaN-based vertical-injection light-emitting diodes with GaN nano-cone structure by ICP etching
(2008-07-25)
Huang, H. W.
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Lin, C. H.
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Yu, C. C.
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Lee, K. Y.
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Lee, B. D.
The GaN-based thin-film vertical-injection LEDs (VLEDs) with GaN nano-cone structures are fabricated and presented. Under the process conditions of fixed Cl(2)/Ar now rate of 10/25sccm and ICP/bias power of 200/200W, the GaN nano-cone structures are self-assembly formed with variable density of 1.5 x 10(7) to 1.4 x 10(1) cm(-2) and variable depth of 0.56-1.34 mu m when varying the ICP chamber pressure. At a driving current of 350mA and with chip size of 1 mm x 1 mm, the light output power of our thin-film LED with a specific GaN nano-cone structure reaches 224 mW which is enhanced by 160% when compared with the output power of conventional VLED. In addition, the corresponding light radiation pattern Shows Much higher light intensity Clue to the strong light scattering effect by the formed nano-cone Structure. (C) 2008 Elsevier B.V. All rights reserved.
Investigation of InGaN/GaN power chip light emitting diodes with TiO(2)/SiO(2) omnidirectional reflector
(2008-12-01)
Huang, H. W.
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Lin, C. H.
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Yu, C. C.
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Lee, B. D.
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Kuo, H. C.
Enhancements of light extraction of GaN-based power chip (PC) LEDs with and without rough surface on p-GaN and TiO(2)/SiO(2) omnidirectional reflector (ODR) on the bottom are presented. Motivated by phosphor-conversion white light applications, the peak-emitting wavelength of our studied PC LEDs is chosen to be 455 nm and the fabricated ODR is designed for the same wavelength regime. At a driving current of 350 mA and a chip size of 1 mm x 1 mm on a TO-can package, the light output power of the PC LED with ODR on the bottom and pit type of rough surface on p-GaN is enhanced by 67% when compared with the same device without ODR and rough surface. Furthermore, by examining the radiation patterns, the PC LED with the ODR and rough surface shows stronger enhancement around the vertical direction. Our results provide promising potential to increase output powers of commercial light emitting devices, especially for white light applications.