Light Extraction Simulation of Surface-Textured Light-Emitting Diodes by Finite-Difference Time-Domain Method and Ray-Tracing Method

概要

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The light extraction efficiency ($\eta_{\text{l}}$) of surface-textured light-emitting diodes (LEDs) is calculated using a simulation based on the combination of the finite-difference time-domain (FDTD) method and the ray-tracing method. Considering the transmittance and light-scattering effects, which depend on the size of the surface-textured structure (STS), we investigated the dependence of $\eta_{\text{l}}$ on the size of the STS including the period and aspect ratio. As a result, a clear dependence on the size of the STS has been shown. Furthermore, by optimizing the size of the STS, we found $\eta_{\text{l}}$ to be about 4 times larger than that of the surface flat structure (SFS). In addition, we demonstrated that the absorption coefficient of the GaN layer ($\alpha_{\text{GaN}}$) affected $\eta_{\text{l}}$ of the STS more strongly than that of the SFS. We suggest that both wide light-scattering and a high GaN crystalline quality are important points for improving $\eta_{\text{l}}$ when texturing the top surface of LEDs.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-01-15