Improved Light Extraction of Nitride-Based Flip-Chip Light-Emitting Diodes Via Sapphire Shaping and Texturing

Author

Huang, Shao-Hua ; Horng, Ray-Hua ; Wen, Kuo-Sheng ; Lin, Yi-Feng ; Yen, Kuo-Wei ; Wuu, Dong-Sing

Author_Institution

Dept. of Mater. Sci. & Eng., Nat. Chung-Hsing Univ., Taichung

Volume

18

Issue

24

fYear

2006

Firstpage

2623

Lastpage

2625

Abstract

A novel flip-chip structure of GaN-sapphire light-emitting diodes (LEDs) was developed to improve the external quantum efficiency, where the sapphire substrate was textured and shaped with beveled sidewalls using a wet etching technique. The forward voltage of the conventional flip-chip and shaped flip-chip GaN LEDs were 2.84 and 2.85 V at 20 mA, respectively. This indicates that the GaN LED was not destroyed during the sapphire wet etching process. It was found that the output power increased from 9.3 to 14.2 mW, corresponding to about 52% increases in the external quantum efficiency. The results agree well with the simulation data that the shaped flip-chip GaN LED can provide better light extraction efficiency than that of the conventional flip-chip sample

Keywords

III-V semiconductors; etching; flip-chip devices; gallium compounds; integrated optoelectronics; light emitting diodes; sapphire; 2.84 V; 2.85 V; 20 mA; 9.3 to 14.2 mW; GaN-Al₂O₃; GaN-sapphire LED; external quantum efficiency; light extraction; light extraction efficiency; light-emitting diodes; nitride-based flip-chip structure; sapphire shaping; sapphire substrate; sapphire texturing; wet etching; Gallium nitride; Light emitting diodes; Liquid crystal displays; Optical scattering; Photonic crystals; Power generation; Substrates; Surface texture; Thermal conductivity; Wet etching; Chip shaping; GaN; flip-chip; light-emitting diode (LED); surface texturing;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2006.886823

Filename

4026613