Paper
25 October 2018 Enhancement of light extraction by ZnO nanostructures on vertical GaN light-emitting diodes
Yuanjie Li, Wenci Sun, Hong Wang, Minyan Zhang, Feng Yun
Author Affiliations +
Abstract
Controllable growth of ZnO nanostructures were realized on the surface patterned vertical-type GaN light emitting diodes (LEDs) by chemical solution method at low temperature. Aqueous ammonia has been added to manipulate the pH values of the growth solution to optimize the morphology of the ZnO nanostructures and light extraction efficiency from GaN LED surface. It is revealed that ZnO nanostructures were mainly grown on the tips of the GaN surface pyramids at pH value of 8.5. With decreasing pH value, ZnO nanostructures were observed grown both on tip and bottom of the GaN pyramids. On the contrary, the growth of ZnO nanostructures was greatly inhibited by increasing pH value above 10. The electroluminescence (EL) spectra intensity was enhanced by 40% for GaN LEDs topped with ZnO nanostructures at pH value of 8.5. This enhancement is attributed to the ZnO nanostructures tip-grown on vertical GaN LEDs effectively reducing the total internal reflection and minimizing Fresnel loss.
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Yuanjie Li, Wenci Sun, Hong Wang, Minyan Zhang, and Feng Yun "Enhancement of light extraction by ZnO nanostructures on vertical GaN light-emitting diodes", Proc. SPIE 10823, Nanophotonics and Micro/Nano Optics IV, 1082317 (25 October 2018); https://doi.org/10.1117/12.2500442
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KEYWORDS
Nanostructures

Zinc oxide

Light emitting diodes

Gallium nitride

Electroluminescence

Scanning electron microscopy

Crystals

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