Abstract
Patterned sapphire substrates (PSSs) in flip chip light-emitting diodes (FC-LEDs) were designed to improve the light extraction efficiencies (LEEs). Two typical types were considered in the cross-section of the PSS pattern; an extruded type and a subtracted type. For pattern shapes in PSS, various polygonal pyramid pattern shapes were also considered, such as triangular-pyramid, square-pyramid, hexagonal-pyramid, circular-pyramids, in addition to hemispheres. Ray-tracing-based numerical simulations were performed for the LEEs of FC-LEDs with various PSSs. The optimal pattern shape for the high LEE was found to be the subtracted type triangular-pyramid shape, which is different from that of the optimal PSS patterns in conventional planar chip LEDs.
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Acknowledgements
This work was supported by the Technology Innovation Program (10067492) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) and by Human Resources Program in the Transportation Specialized Lighting Core Technology Development (No. N0001364) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea.
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Cui, H., Park, SH. Design of patterned sapphire substrates in flip-chip LEDs for improvement of light-extraction efficiencies. Opt Quant Electron 50, 140 (2018). https://doi.org/10.1007/s11082-018-1414-3
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DOI: https://doi.org/10.1007/s11082-018-1414-3