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The Scientific World Journal
Volume 2012 (2012), Article ID 515468, 6 pages
http://dx.doi.org/10.1100/2012/515468
Research Article

Double-Grating Displacement Structure for Improving the Light Extraction Efficiency of LEDs

1College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China
2Mechanical Science and Engineering Institute, Northeast Petroleum University, Daqing 163318, China

Received 1 September 2012; Accepted 18 September 2012

Academic Editors: B. Chen, T. Han-Song, and C. Zhan-Ming

Copyright © 2012 Zhibin Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To improve the light extraction efficiency of light-emitting diodes (LEDs), grating patterns were etched on GaN and silver film surfaces. The grating-patterned surface etching enabled the establishment of an LED model with a double-grating displacement structure that is based on the surface plasmon resonance principle. A numerical simulation was conducted using the finite difference time domain method. The influence of different grating periods for GaN surface and silver film thickness on light extraction efficiency was analyzed. The light extraction efficiency of LEDs was highest when the grating period satisfied grating coupling conditions. The wavelength of the highest value was also close to the light wavelength of the medium. The plasmon resonance frequencies on both sides of the silver film were affected by silver film thickness. With increasing film thickness, plasmon resonance frequency tended toward the same value and light extraction efficiency reached its maximum. When the grating period for the GaN surface was 365 nm and the silver film thickness was 390 nm, light extraction efficiency reached a maximum of 55%.