DocumentCode :
1116211
Title :
Current Spreading and Blocking Designs for Improving Light Output Power from the Vertical-Structured GaN-Based Light-Emitting Diodes
Author :
Chen, Tron-Min ; Wang, Shui-Jinn ; Uang, Kai-Ming ; Kuo, Hon-Yi ; Tsai, Ching-Chung ; Lee, Wei-Chi ; Kuan, Hon
Author_Institution :
WuFeng Inst. of Technol., Chia-Yi
Volume :
20
Issue :
9
fYear :
2008
fDate :
5/1/2008 12:00:00 AM
Firstpage :
703
Lastpage :
705
Abstract :
In this work, use of localized Ti deposition associated with a transparent indium-zinc-oxide (IZO) layer is proposed to serve as Schottky current blocking and current spreading layer, respectively. In addition, an inductively coupled plasma (ICP) mesa etching on the surface layer (n-GaN) of regular vertical-conducting metal-substrate GaN-based light-emitting diodes (VM-LEDs) is also proposed to further enhance current spreading of the device. Through a two-dimensional device simulator, the calculated results indicate that significant avoidance of the current-crowding effect under cathode contact pad could be obtained once the n-GaN layer etching depth and width, IZO thickness, and Schottky current blocking width have been optimized. In experiments, 1000 m 1000 m GaN-based blue LEDs with an ICP mesa etching of 250 m in width and 2 m in depth on the surface n-GaN layer, 200 m in Schottky current blocking width, and a 300-nm-thick IZO layer have the been successfully fabricated. As compared to the regular VM-LEDs without the use of the present technology, typical improvement in light emission uniformity and light output power by about 6% and 38% at an injection current of 350 mA have been obtained.
Keywords :
III-V semiconductors; etching; gallium compounds; light emitting diodes; wide band gap semiconductors; GaN; InZnO; Schottky current blocking; blue LED; cathode contact pad; current 350 mA; current spreading layer; current-crowding effect; depth 2 mum; etching depth; inductively coupled plasma mesa etching; injection current; light emission; light output power; size 1000 mum; size 200 mum; size 250 mum; size 300 nm; surface layer; transparent indium-zinc-oxide layer; vertical-conducting metal-substrate light-emitting diodes; Cathodes; Etching; Gallium nitride; Light emitting diodes; Nickel; Optical coupling; Plasma applications; Plasma devices; Plasma simulation; Power generation; Current blocking; GaN; current spreading; current-crowding effect (CCE); light output power (${L}_{rm op}$); light-emitting diodes (LEDs);
fLanguage :
English
Journal_Title :
Photonics Technology Letters, IEEE
Publisher :
ieee
ISSN :
1041-1135
Type :
jour
DOI :
10.1109/LPT.2008.920031
Filename :
4479613
Link To Document :
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