Patterned sapphire substrate (PSS) technique has been widely used to improve the performance of the GaN-based LEDs, because it is helpful for both internal quantum efficiency and light extraction efficiency. In this study, patterned sapphire substrates with different pattern morphology are fabricated by wet etching. The light angular distribution of LED can be adjusted as the pattern morphology on sapphire surface of LED is changed. We perform the white LEDs packaging with the chessboard phosphor structures. The blue light emitted from GaN die chip can be converted into white light more efficiently, due to the chessboard phosphor structures. We can select specific light angular distribution of LED fitting the chessboard phosphor structure to obtain the optimal white light packaging efficiency. The highest packaging efficiency of the chessboard packaging is 70.87 % at color temperature of daylight 6500 K +/- 500 K. The increasing packaging efficiency is contributed by well geometric matching between the light angular distribution of LED and the the chessboard phosphor structure. Thus, our experiment almost achieves the limitation of the chessboard packaging efficiency in simulation: 74.30 %.

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Shih-Wei Huang, "Using chessboard phosphor structure and patterned sapphire substrate technique to enhance white LED packaging efficiency (Conference Presentation)," Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 105321Y (Presented at SPIE OPTO: February 01, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2288290.5751529787001.