Issue 8, 2014

Light-extraction enhancement of a GaN-based LED covered with ZnO nanorod arrays

Abstract

We investigate the mechanism of light extraction enhancement of a GaN-based light-emitting diode (LED) grown on patterned sapphire substrate (PSS), that has ZnO nanorod arrays (NRAs) fabricated on top of the device using the hydrothermal method. We found that the light output power of the LED with ZnO NRAs increases by approximately 30% compared to the conventional LED without damaging the electrical properties of the device. We argue that the gradual decrease of the effective refractive index, which is caused by the fabrication of ZnO NRAs, is the mechanism of the observed improvement. Our argument is confirmed by cross-sectional confocal scanning electroluminescence microscopy (CSEM) and the theoretical simulations, where we observed a distinct increase of the transmission at the interface between LED and air at the operation wavelength of the LED. In addition, the plane-view CSEM results indicate that ZnO NRAs, which were grown on the bare p-type GaN layer as an electrical safety margin area, also contribute to the enhanced light output power of the LED, which indicate further enhancement is manifested even in the optically ineffective sacrificial area.

Graphical abstract: Light-extraction enhancement of a GaN-based LED covered with ZnO nanorod arrays

Supplementary files

Article information

Article type
Paper
Submitted
12 Dec 2013
Accepted
19 Jan 2014
First published
14 Mar 2014

Nanoscale, 2014,6, 4371-4378

Light-extraction enhancement of a GaN-based LED covered with ZnO nanorod arrays

H. Jeong, D. J. Park, H. S. Lee, Y. H. Ko, J. S. Yu, S. Choi, D. Lee, E. Suh and M. S. Jeong, Nanoscale, 2014, 6, 4371 DOI: 10.1039/C3NR06584G

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