The use of transparent indium–zinc oxide/(oxidized-Ni/Au) ohmic contact to GaN-based light-emitting diodes for light output improvement

Abstract

In this study, a low-resistant and high-transparent ohmic contact to p-GaN layer using an indium–zinc oxide (IZO)/(oxidized-Ni/Au) contact system was investigated to enhance light extraction of GaN-based light-emitting diodes (LEDs). Improvement in the light output of GaN-based blue LEDs as a function of the IZO film thickness was examined and an optimum thickness of around 300 nm has been found. Under an injection current in the 10−50 mA range, as compared to the case without IZO film, about 35−28% improvement in light output power (Lop) has been obtained. Comparisons of Lop and its reliability for LEDs with an IZO or indium–tin oxide transparent conduction layer were also made. In addition, compared to IZO/GaN samples without the patterned surface, the LEDs fabricated using a patterned IZO surface show a 23.1% improvement in Lop at 20 mA.