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Presentation
Top Transmission Grating GaN LED Simulations for Light Extraction Improvement
Proceedings of SPIE 2011, San Francisco, CA
  • Simeon Trieu, California Polytechnic State University - San Luis Obispo
  • Xiaomin Jin, California Polytechnic State University - San Luis Obispo
  • Ashton Ellaboudy, California Polytechnic State University - San Luis Obispo
  • Bei Zhang, Peking University
  • Xiang-Ning Kang, Peking University
  • Guo-Yi Zhang, Peking University
  • Xiong Chang, Peking University
  • Wei Wei, Peking University
  • Sun Yong Jian, Peking University
  • Fu Xing Xing, Peking University
Publication Date
1-24-2011
Abstract

We study the top transmission grating’s improvement on GaN LED light extraction efficiency. We use the finite difference time domain (FDTD) method, a computational electromagnetic solution to Maxwell’s equations, to measure light extraction efficiency improvements of the various grating structures. Also, since FDTD can freely define materials for any layer or shape, we choose three particular materials to represent our transmission grating: 1) nonlossy p-GaN, 2) lossy indium tin oxide (ITO), and 3) non-lossy ITO (α=0). We define a regular spacing between unit cells in a crystal lattice arrangement by employing the following three parameters: grating cell period (Α), grating cell height (d), and grating cell width (w). The conical grating model and the cylindrical grating model are studied. We also presented in the paper directly comparison with reflection grating results. Both studies show that the top grating has better performance, improving light extraction efficiency by 165%, compared to that of the bottom reflection grating (112%), and top-bottom grating (42%). We also find that when grating cells closely pack together, a transmission grating maximizes light extraction efficiency. This points our research towards a more closely packed structure, such as a 3-fold symmetric photonic crystal structure with triangular symmetry and also smaller feature sizes in the nano-scale, such as the wavelength of light at 460 nm, half-wavelengths, quarter wavelengths, etc.

Number of Pages
11
Publisher statement
One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Citation Information
Simeon Trieu, Xiaomin Jin, Ashton Ellaboudy, Bei Zhang, et al.. "Top Transmission Grating GaN LED Simulations for Light Extraction Improvement" Proceedings of SPIE 2011, San Francisco, CA Vol. 7933 (2011)
Available at: http://works.bepress.com/xjin/32/