Title :
Luminance Enhancement of Flip-Chip Light-Emitting Diodes by Geometric Sapphire Shaping Structure
Author :
Lee, C.E. ; Kuo, H.C. ; Lee, Y.C. ; Tsai, M.R. ; Lu, T.C. ; Wang, S.C. ; Kuo, C.T.
Author_Institution :
Nat. Chiao Tung Univ., Hsinchu
Abstract :
The flip-chip light-emitting diodes (FC-LEDs) with geometric sapphire shaping structure were investigated. The sapphire shaping structure was formed on the bottom side of the sapphire substrate by a chemical wet etching technique for light extraction purpose. The crystallography-etched facets were (1010) M-plane, (1102) R-plane, and (1120) A-plane against the (0001) c-axis with the angles range between 29deg~60deg. These large slope oblique sidewalls are useful for light extraction efficiency enhancement. The light-output power of sapphire shaping FC-LEDs was increased 55% (at 350-mA current injection) compared to that of conventional FC-LEDs.
Keywords :
III-V semiconductors; brightness; etching; flip-chip devices; gallium compounds; light emitting diodes; wide band gap semiconductors; Al2O3; GaN; LED; chemical wet etching technique; crystallography-etched facets; current injection; flip-chip light-emitting diodes; geometric sapphire shaping structure; light extraction; light extraction efficiency; light-output power; luminance enhancement; sapphire substrate; Brightness; Chemicals; Crystallography; Life members; Light emitting diodes; Optical reflection; Photonic band gap; Quantum well devices; Thermal conductivity; Wet etching; Flip-chip light-emitting diodes (FC-LEDs); geometric sapphire shaping; oblique sidewall; sapphire wet etching;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2007.912990
