Self-Assembled Two-Dimensional Surface Structures for Beam Shaping of GaN-Based Vertical-Injection Light-Emitting Diodes

Abstract

Abstract-Enhanced light extraction and beam shaping of GaN-based vertical-injection light-emitting diodes (VI-LEDs)employing biomimetic surface structures were demonstrated. The biomimetic surface structures were fabricated using self-assembled polystyrene nanospheres serving as a monolayer mask, and followed by anisotropic inductively coupled plasma reactive ion etching. The light output power of the VI-LEDs with the patterned structures exhibited an efficiency enhancement factor of 68% at a driving current of 350 mA, compared to those without any surface structures. The structures also resulted in a modified heart-shaped radiation pattern, which is preferable for backlight applications in flat panel displays.

Heat and fluid flow in high-power LED packaging and applications

“…As expected, the results shown inFig. 14(f)indicate that the light output power of the top surface textured LEDs is much higher than conventional LEDs, which demonstrates that the top surface textures can improve LEE[55].…”

“…Photons generated by radiative recombination may not be able to escape from the LED chip if they are totally internally reflected at the semiconductor-air interface. If the incident angle of the light ray is close to normal, they are effectively extracted outside of the LED chip; otherwise, they will be trapped inside [21] [51,53,55]. In addition, the direction of the emission light is unconfined, resulting in a Lambertian radiation pattern.…”

Highly Efficient and Bright LEDs Overgrown on GaN Nanopillar Substrates

“…A 2-D finite difference time domain (FDTD) simulation was applied to calculate the LEE of the LEDs using the FullWAVE program [34]. The calculated electric-field distribution with air-void period of 0.25 μm is shown in Fig.…”

Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer

“…3-D finite difference time domain (FDTD) simulation was applied to calculate the LEE of the LEDs using the FullWAVETM program [30]. A 5 Â 5 periodic triangle pyramidal array PSS with a height of 6.22 μm was employed in the simulation structure.…”