Improving the extraction efficiency of planar GaN-based blue light-emitting diodes via optimizing indium tin oxide nanodisc arrays

Abstract

We report an enhancement in light emission of a GaN-based blue light-emitting diode (LED) with periodic indium tin oxide (ITO) nanodisc arrays. The periodic nanodisc arrays were elaborately designed by the Bragg diffraction and the maximum transmittance of a model of bilayer film on a GaN epitaxial layer. In the experiment, the periodic ITO nanodisc arrays have been fabricated by polystyrene nanosphere lithography. The electroluminescence intensity of the LEDs with periodic ITO nanodisc arrays is better than that of conventional planar GaN-based LED, and the greatest enhancement could increase the intensity by a factor of 2.08 at an operating current of 20 mA compared with the conventional planar GaN-based LED. The simulation results based on three-dimensional finite difference time-domain method showed that the LED with periodic ITO nanodisc arrays can improve the light-extraction efficiency of LED by enhancing the critical angle of light output. This method would be valuable for the fabrication of high-efficiency planar GaN-based LEDs.