Performance Improvement of GaN-Based Light-Emitting Diodes With a Microhole Array, 45° Sidewalls, and a SiO2 Nanoparticle/Microsphere Passivation Layer

Abstract

The characteristics of GaN-based light-emitting diodes (LEDs) with a hybrid structure incorporating a microhole array, 45 sidewalls, and an appropriate SiO2 nanoparticle (NP)/microsphere (MSs) passivation layer are studied and reported. The use of a SiO2 NP/MSs passivation layer causes a remarkable reduction in reverse-biased leakage current. The employment of this hybrid structure leads to substantial enhancements in optical properties without any degradation in electrical performance. In addition, a lower content of SiO2 NP in the mixed SiO2 NP/MSs solution leads to enhanced optical behavior due to the improved transmittance. Experimentally, as compared with a conventional LED (Device A), the studied Device E shows 50.6%, 50.9%, 48.4%, and 49.9% enhancements in light output power, luminous flux, luminous efficacy, and wall-plug efficiency, respectively. These advantages are mainly attributed to the increased scattering probability and the opportunity to find photon escape cones as well as the reduced total internal reflection and Fresnel reflection effects. Therefore, the studied hybrid structure provides a promise for high-performance GaN-based LED applications.