Enhancement in output power of blue gallium nitride-based light-emitting diodes with omnidirectional metal reflector under electrode pads

In this study, we demonstrate a GaN-based light-emitting diode (LED) with nonalloyed metal contacts onto the n+ -GaN surface and transparent contact layer (indium tin oxide) to serve as the n -type electrode (cathode) and the p -type electrode pad (anode), respectively. Comparing with the conventional LEDs, which the electrode pads and/or Ohmic contacts form through conventional CrAu metal contacts, the nonalloyed metal contacts (AgCrAu or AlCrAu) used in the present experimental blue LEDs also play the role of reflector to prevent the emitted light from absorption by the opaque electrode pads with low reflectivity (CrAu). With an injection current of 20 mA, the enhancement in the light output power has approximately a 14% magnitude compared to the GaN-based LEDs without Ag or Al reflectors under the CrAu electrode pads.