Optimization of indium tin oxide layer thickness for surface-plasmon-enhanced green light-emitting diodes

Abstract

Surface-plasmon (SP)-enhanced light-emitting diodes (LEDs) covering self-assembled Ag nanoparticles (NPs) on top of a p-GaN layer are broadly studied to improve luminescence efficiency in green LEDs. However, the enhancement factor of SP-enhanced LEDs is reduced under electrical injection compared to that under external optical pumping. For current injection, indium tin oxide (ITO) is typically deposited on top of a p-GaN layer for current spreading and ohmic contact. In this paper, we investigate the effect of the ITO layer on the performance of SP-enhanced green LEDs. We prepared samples with varying ITO thicknesses, from 30 nm to 200 nm, and investigated their optical and electrical characteristics. From the ITO thickness-dependent measurements, we show ITO thickness has a significant impact on electroluminescence intensity and current-voltage characteristics. Finally, we propose the optimized ITO thickness for SP-enhanced LEDs.