Browsing by Author "Peng, Wei Chih"

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Effect of the silver mirror location on the luminance intensity of double-roughened GaN light-emitting diodes
(2007)
Wu, YewChung Sermon
;
Liao, Cheng
;
Peng, Wei Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Three kinds of GaN light-emitting diodes (LEDs) were used to investigate the effect of the silver (Ag) mirror location on the performance of LEDs. Samples designated as "PR-LED" were LEDs with roughened p-GaN surface. "DRM-LED" and "DRSM-LED" were LEDs with double-roughened (p-GaN and undoped-GaN) surfaces and a Ag mirror system either at the undopedGaN/sapphire interface or on the back side of sapphire substrate. It was found that the light intensity of DRM-LED was 235.8 mcd, which was 3.05 times higher than that of the PR-LED, and 1.45 times higher than that of the DRSM-LED. (c) 2007 The Electrochemical Society.
Effects of Laser Sources on Damage Mechanisms and Reverse-Bias Leakages of Laser Lift-Off GaN-Based LEDs
(2009)
Cheng, Ji-Hao
;
Wu, YewChung Sermon
;
Peng, Wei Chih
;
Ouyang, Hao
;
材料科學與工程學系
The frequency-tripled neodymium-doped yttrium aluminum garnet laser (355 nm) and the KrF pulsed excimer laser (248 nm) were employed to separate GaN thin films from sapphire substrates and to transfer the films to bond with other substrates. The different laser lift-off processes would generate the dislocation density on different regions. In this study, the effects of these two laser sources on structural damage mechanisms and reverse-bias leakages of InGaN-GaN light-emitting diodes (LEDs) were studied.
Effects of laser sources on the reverse-bias leakages of laser lift-off GaN-based light-emitting diodes
(2007-06-18)
Wu, Yewchung Sermon
;
Cheng, Ji-Hao
;
Peng, Wei Chih
;
Ouyang, Hao
;
材料科學與工程學系
The KrF pulsed excimer laser (248nm) and the frequency-tripled neodymium doped yttrium aluminum garnet laser (355nm) have been used to separate GaN thin films from sapphire substrates and transfer to bond other substrate. However, these processes would increase the dislocation density, resulting in an increase of the leakage current. In this study, the effects of these two laser sources on the reverse-bias leakages of InGaN-GaN light-emitting diodes were studied. (c) 2007 American Institute of Physics.
Improved luminance intensity of InGaN-GaN light-emitting diode by roughening both the p-GaN surface and the undoped-GaN surface
(2006-07-24)
Peng, Wei Chih
;
Wu, Yew Chung Sermon
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The InGaN-GaN epitaxial films were grown by low-pressure metal-organic chemical vapor deposition on a sapphire substrate, and then the light-emitting diode (LED) with double roughened (p-GaN and undoped-GaN) surfaces was fabricated by surface-roughening, wafer-bonding, and laser lift-off technologies. It was found that the front side luminance intensity of double roughened LED was 2.77 times higher than that of the conventional LED at an injection current of 20 mA. The backside luminance intensity was 2.37 times higher than that of the conventional LED. This is because the double roughened surfaces can provide photons multiple chances to escape from the LED surface, and redirect photons, which were originally emitted out of the escape cone, back into the escape cone.