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 Cr/Au metal contacts, the nonalloyed metal contacts (Ag/Cr/Au or Al/Cr/Au) 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 (Cr/Au). 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 Cr/Au electrode pads. (c) 2008 American Institute of Physics.