Improvement of the light output and contact resistance of InGaN-based light-emitting diodes based on tantalum-doped indium tin oxide as p-type electrodes

This paper reports that highly transparent and low resistance tantalum-doped indium tin oxide (Ta-doped ITO) films contacted to p-type GaN have been prepared by the electron-beam evaporation technique. The Ta-doped ITO contacts become Ohmic with a specific contact resistance of ~ 5.65 × 10−5 Ωcm2 and show the transmittance of ~98% at a wavelength of 440 nm when annealed at 500 °C. Blue light emitting diodes (LEDs) fabricated with Ta-doped ITO p-type Ohmic contact layers give a forward-bias voltage of 3.21 V at an injection current of 20 mA. It further shows that the output power of LEDs with Ta-doped ITO contacts is enhanced 62% at 20 mA in comparison with that of LEDs with conventional Ni/Au contacts.