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.

Design of photonic crystals for light‐emitting diodes

“…After repeated reflections from the medium around it, the majority of the light released from the general LED luminous center is not properly radiated from the LEDs, which results in the light radiation efficiency being very poor. Therefore, the external radiation efficiency of ordinary LEDs is only about 3% 5–8 . In addition to the low monochromaticity of LED lights, high costs, potential damage to human eyes, and other drawbacks, this presented a significant barrier to the development of future lighting technologies.…”

“…Therefore, the external radiation efficiency of ordinary LEDs is only about 3%. [5][6][7][8] In addition to the low monochromaticity of LED lights, high costs, potential damage to human eyes, and other drawbacks, this presented a significant barrier to the development of future lighting technologies. Consequently, boosting the light extraction efficiency (LEE) of LEDs is vital for replacing current lighting sources, and research linked with this endeavor is critical for speeding the expansion of the present lighting sector.…”