Enhanced light output power of GaN-based light-emitting diodes by nano-rough indium tin oxide film using ZnO nanoparticles

We demonstrate the performance improvement of GaN-based light-emitting diodes (LEDs) using zinc oxide (ZnO) nanoparticles inserted between the p-GaN and the indium tin oxide (ITO) layers. Upon deposition of an ITO film over the dispersed ZnO nanoparticles, the ITO surface tends to attain a nano-rough morphology due to the presence of ZnO nanoparticles. The light output power of the fabricated LEDs with ZnO nanoparticles is 39% higher than that of conventional LEDs at an injection current of 20 mA. This is attributed to the improved light extraction favored by the light scattering tendency of ZnO nanoparticles and the nano-roughened ITO film. In addition, the intermediate refractive index (n similar to 2) of ZnO materials between those of the p-GaN (n similar to 2.5) and the ITO (n similar to 1.9) results in a broader critical angle and a reduction of total internal reflection. (C) 2011 American Institute of Physics. [doi:10.1063/1.3575174]