Fabrication and theoretical analysis of GaN-based vertical light-emitting diodes with SiO2 current blocking layer

Abstract

We report the fabrication and characteristics of 1 × 1 mm2 blue vertical light-emitting diodes (VLEDs) with a SiO2 current blocking layer (CBL), together with their theoretical analysis in terms of electrical, optical and thermal properties. The SiO2 CBL improves the total light extraction efficiency by relieving the current crowding under the metal n-electrode. Additionally, the total light extraction efficiency of LEDs with SiO2 CBL remains almost the same independent of injection current, whereas that of conventional VLEDs is gradually decreased with injection current. The optical output power (Pout) for the VLED with SiO2 CBL is increased by about 10% at 350 mA in a wafer level without serious degradation in operating voltage resulting from the insertion of SiO2 CBL, thus resulting in a high Pout of 670 mW at 950 mA. The simulated light–current–voltage characteristics of the fabricated devices were reasonably consistent with the measured results.