Light Extraction Enhancement of GaN-Based Light-Emitting Diodes Using Hollow Silica Nanospheres

We report a method for enhancing light extraction in GaN-based light-emitting diodes (LEDs) using hollow silica (SiO2) nanospheres (HSNs). To create the HSNs formed on the surface of the LED, a polystyrene (PS) core was removed by a thermal annealing process from synthesized PS/SiO2 core/shell structures. HSN-coated LEDs show a dramatic improvement in electroluminescence (EL) intensity among different surface structured LEDs coated with bare silica nanospheres and without any nanostructures. The finite-difference time-domain simulation results are in accordance with experimentally observed ones. The enhancement in EL intensity using HSNs coated LED can be attributed to the increase in the probability of light escape by reducing Fresnel reflection and by frequent light scattering within the nanospheres.