Light-output enhancement of GaN-based light-emitting diodes by photoelectrochemical oxidation in H2O

Abstract

The light output of GaN-based light-emitting diodes (LEDs) was improved by an oxide film being directly grown on the p-GaN surface utilizing photoelectrochemical (PEC) oxidation via H2O. The light outputs of the LEDs were enhanced by approximately 16 and 37% after 30 and 45 min PEC oxidation, respectively, compared to those of a conventional LED at 20 mA, and the PEC oxidized LEDs exhibited almost the same dynamic resistance (R = dV/dI) as conventional LEDs without PEC oxidation. Atomic force microscopy (AFM) data show that the roughness of the interface between oxide film and p-GaN increases with oxidation time. In addition, the oxide film on the top surface of the GaN-based LED caused the antireflection effect and the changes of the surface effective refractive indices consequently increased the critical angle and in caused more light to be emitted from the GaN-based LED.