Browsing by Author "Yen, His-Hsuan"

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Directional light extraction enhancement from GaN-based film-transferred photonic crystal light-emitting diodes
(2009-03-23)
Lai, Chun-Feng
;
Chao, Chia-Hsin
;
Kuo, Hao-Chung
;
Yen, His-Hsuan
;
Lee, Chia-En
Experimental investigation of the directionality in the far-field pattern and light extraction enhancement in collected cone were performed in GaN-based film-transferred photonic crystal (PhC) light-emitting diodes (FTLEDs). Angular-resolved measurement revealed directional profile and azimuthal anisotropy in the far-field distribution with guided modes extraction. Good agreement according to Bragg's diffraction theory and free photon band structure were achieved. The light enhancement in PhC FTLEDs compared to non-PhC FTLEDs within the collection cone angle was obtained according to measured three-dimensional far-field patterns. In a +/- 20 degrees collection cone, collected light was enhanced by a factor of similar to 2.4 for the collimated PhC FTLED.
Divergent Far-Field III-Nitride Ultrathin Film-Transferred Photonic Crystal Light-Emitting Diodes
(2010)
Lai, Chun-Feng
;
Chao, Chia-Hsin
;
Kuo, Hao-Chung
;
Yu, Peichen
;
Yen, His-Hsuan
The divergent far-field distribution of III-nitride ultrathin film-transferred light-emitting diodes (FTLEDs) with ellipse holes of triangular photonic crystal (PhC) lattice have been experimental and theoretical studies. Angular-and-spectral-resolved measurement revealed guided modes extraction behaviors which obtain good agreement with theoretical model according to two-dimensional free photon band structure. The azimuthal evolution of the guided modes' diffraction behavior according to Bragg's diffraction has also been discussed by angular-resolved monochromatical mapping. Finally, the PhC FTLEDs show light enhancement with the divergence far-field pattern that exhibited 130% at a driving current of 200mA as compared with non-PhC (without PhC) FTLEDs. This could lead to promising LEDs with unusual divergent far-field properties for specific applications. (C) 2010 The Japan Society of Applied Physics
GaN Thickness Effect on Directional Light Enhancement from GaN-Based Film-Transferred Photonic Crystal Light-Emitting Diodes
(2010)
Lai, Chun-Feng
;
Chao, Chia-Hsin
;
Kuo, Hao-Chung
;
Yu, Peichen
;
Yen, His-Hsuan
Directional light enhancement behavior including collimated far-field patterns sensitively depending on both photonic crystal (PhC) lattice constant and GaN thickness from GaN film-transferred light-emitting diodes (FTLEDs) with a triangular PhC lattice has been experimentally studied. Far-field pattern measurement in the Gamma-M and Gamma-K directions of GaN PhC FTLEDs with various lattice constants and GaN thicknesses revealed different far-field profiles as detemined on the basis of guided mode extraction of Bragg's diffraction. Additionally, three-dimensional (3D) far-field measurement revealing the PhC diffraction patterns was also demonstrated. We also used the 3D finite-different time-domain method to confirm the experimental results. (C) 2010 The Japan Society of Applied Physics