Schematic diagrams of conventional flip-chip bulk-GaN LEDs (a)and truncated-pyramidal-shaped flip-chip bulk-GaN LEDs (b).
The light escape cones of rectangular-shaped LEDs (a), truncated-pyramidal-shaped LEDs with inclination angle 20° (b), 44° (c); and the corresponding electric field distribution (d), (e), and (f) simulated by FDTD.
Light extraction efficiency of conventional rectangular bulk-GaN LEDs (a), triangle- and hexagon-shaped bulk-GaN LEDs (b) as a function of inclination angle using ray-trace simulation(with the dimension of 1000 μm × 1000 μm, thickness of 350 μm).
Light extraction efficiency of rectangle-shaped LEDs (a), triangle-shaped (b), and hexagon-shaped (c)bulk-GaN LEDs chip as a function of dimension and inclination angle.
(a) L-I characteristics of thetruncated-pyramidal-shaped LEDs (from inclination angle 0° to 50°, respectively) and reference LEDs, and the insets shows the I-V curve of LEDs before and after laser shaping, (b) tilt view, and (c) cross-section view of optical micrographs of truncated-pyramidal-shaped LEDs (with inclination angle 44°) at 5 mA injection current.
(a) The simulated emission patterns obtained from ray tracing using LED models of truncated-pyramidal-shaped LEDs (the inclination angle 44°) and the reference LEDs (rectangle-shaped LEDs chip with vertical sidewalls), (b) the corresponding experiment results, and (c) the sidewall emission pattern of truncated-pyramidal-shaped LEDs (the inclination angle 44°).
Parameters of each layer in the simulated LED.
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