Improvement of the light output of InGaN-based light-emitting diodes using Cu-doped indium oxide/indium tin oxide p-type electrodes

We report on the formation of highly transparent and low-resistance Cu-doped indium oxide(CIO)(3 nm)/indium tin oxide (ITO) (400 nm) ohmic contact to p-type GaN for high-brightness light-emitting diodes (LEDs) for solid-state lighting. The CIO/ITO contacts become ohmic with specific contact resistances of ∼10−4Ωcm2 and give transmittance higher than 98.7% at a wavelength of 405 nm when annealed at 630 °C for 1 min in air. Near UV LEDs fabricated with the annealed CIO/ITO p-type contact layers give a forward-bias voltage of 3.25 V at injection current of 20 mA. It is further shown that the output power of the LEDs with the CIO/ITO contacts is enhanced 78% at 20 mA as compared with that of LEDs with the conventional Ni∕Au contacts.