Enhancement of the light output performance for GaN-based light-emitting diodes by bottom pillar structure

Abstract

A three-dimensional model with finite difference and time domain was established to investigate the enhancement of the light output intensity of GaN light-emitting diodes ͑LEDs͒ with bottom pillar ͑BP͒ structure. Through comparing the normalized light extraction intensity of GaN LEDs with or without BP in different dimensions, the theoretical results show that the light output intensity in the LED with BP structure involved could be enhanced by about 30%. The influence of BP structure on the light output intensity of a LED could be explained by the physical model of light interaction. In addition, the experimental results also show the same trend to the theoretical calculations.

Fabrication of moth-eye structure on p-GaN layer of GaN-based LEDs for improvement of light extraction

“…To solve this problem, there have been many studies on texturing methods, such as photonic crystals [2][3][4], roughening surface [5][6][7], and patterned sapphire substrate (PSS) [8][9][10]. The present study considered the insertion of a moth-eye structure into the InGaNbased LEDs to improve the light extraction efficiency.…”

High Responsivity in GaN Ultraviolet Photodetector Grown on a Periodic Trapezoid-Column Patterned Sapphire Substrate

“…For the same area of the sapphire substrate, a reduced geometrical size of sapphire patterns can increase the number of patterns, and thus increase the opportunity for light scattering from the PSS. (30,31) In addition, a geometrical pattern of a suitable shape and sidewall angle on the sapphire substrate can also increase the reflection of unabsorbed photons resulting in more photogenerated carriers as embedded reflectors, in accordance with Snell's law.…”

Pattern-size dependence of characteristics of nitride-based LEDs grown on patterned sapphire substrates

“…Besides, changing the pattern size of the PSS could improve the light extraction of the LEDs. For the same area of the sapphire substrate, the smaller pattern size of the PSS can increase the number of the patterns, and then increase the opportunity of light scattering [14,15]. In this study, we investigate the pattern-size dependence of structural, electrical and optical properties of GaN-based LEDs grown on the PSS.…”

“…Using epitaxial lateral overgrowth (ELOG) technique, threading dislocations could be significantly eliminated [3][4][5], but the two-step growth procedure is time consuming. Recently, the single growth technique by introducing patterned sapphire substrates (PSS) has been extensively researched for improving the crystalline quality and the light extraction of the LEDs [6][7][8][9][10][11][12][13][14][15].…”