Enhanced Light Emission of InGaN Light-Emitting-Diodes by Nanosphere Lithography Generated Photonic Crystals with Different Geometries

Abstract

This paper has proposed a simple, low-cost and high-throughput method to fabricate the pillar, cone and volcano photonic crystal (PhC) light-emitting diodes (LEDs) on the p-GaN surface using self-assembled nanosphere lithography (NSL) process to improve the light emission of InGaN-based light-emitting diodes (LEDs). A monolayer of self-assembled nanospheres has served as an etching mask for pattern transfer to the p-GaN layer, resulting in hexagonal PhC arrays with different geometrical patterns. Among the different patterns, LEDs with volcano PhC structures have exhibited the best optical property. At inject current of 350 mA, the light output power (LOP) of the volcano PhC LEDs has been enhanced by 43%, compared to that of the conventional LEDs. The volcano PhC LEDs have also exhibited emission divergence angle reduction of 19.8° with respect to the conventional ones. Their emission characteristics and mechanisms have been further investigated with finite-difference time-domain (FDTD) simulations.