Browsing by Author "Liao, Cheng"

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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
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Liao, Cheng
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Peng, Wei Chih
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材料科學與工程學系
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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.
Improved Performance of InGaN-GaN Light-Emitting Diode by a Periodic n-Bowl Mirror Array
(2009)
Liao, Cheng
;
Wu, YewChung Sermon
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A periodic n-bowl mirror structure was introduced into light-emitting diodes with roughened p-GaN surface (RP-LED) by wafer bonding and laser lift-off technology. The performance of these n-bowl mirror light-emitting diodes (NBM-LEDs) was better than that of RP-LED. Besides, the light intensity and the output power of NBM-LEDs were increased with the decrease in n-bowl dimension. The view angle was decreased with the diameter of the n-bowl.
InGaN-GaN Light Emitting Diode Performance Improved by Roughening Indium Tin Oxide Window Layer via Natural Lithography
(2010)
Liao, Cheng
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Wu, YewChung Sermon
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材料科學與工程學系
;
Department of Materials Science and Engineering
A simple natural lithography process was employed to roughen the indium tin oxide (ITO) window layer to improve the performance of an InGaN-GaN light emitting diode (LED). In this process, a photoresist layer was used as a mask for inductively coupled plasma (ICP) dry etching. The photoresist was distorted during the ICP etching process. As the etching time increased, the distorted shapes of the photoresist were transferred to the ITO surface. The roughness of the ITO surface can be easily controlled by the thickness of the photoresist mask. Moreover, the performance of LEDs increased with the thickness of the photoresist mask. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3257601] All rights reserved.
Laser Lift-Off Mechanisms of GaN Epi-Layer Grown on Pattern Sapphire Substrate
(2015-01-01)
Chang, Tai-Min
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Fang, Hsin-Kai
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Liao, Cheng
;
Hsu, Wen-Yang
;
Wu, YewChung Sermon
Wafer bonding and laser lift-off (LLO) processes were employed to fabricate pattern sapphire thin-GaN light-emitting diodes LEDs (PT-LED). During the LLO process, the required laser energy for PT-LED was much higher than that for flat thin-GaN LED (FT-LED). The yield rate of PT-LED was low, and the leakage current was high. In this study, the laser lift-off mechanisms of PT-LEDs were investigated. (C) The Author(s) 2014. Published by ECS. All rights reserved.