Title :
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
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;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2006.886823
