Enhanced emission efficiency of GaN∕InGaN multiple quantum well light-emitting diode with an embedded photonic crystal

Abstract

A photonic crystal (PC) structure of periodic SiO2 pillar cubic array is embedded in n-GaN layer of InGaN∕GaN multiple quantum well (MQW) blue (480nm) light-emitting diode (LED). The diameter, period, and depth of SiO2 pillar are 124±6, 230±10, and 130±10nm, respectively. The increments of 70% for external quantum efficiency, 17% for internal quantum efficiency, and 45% for light extraction efficiency from photoluminescence measurement, and 33% for optical output power at 20mA are observed for LEDs with an embedded PC layer. This improvement can be attributed to the increased extraction efficiency by PC effect as well as increased internal quantum efficiency due to the decrease of dislocation density in n-GaN layer because of an epitaxial lateral over-growth process.