Formation of Low Resistance and High Reflectivity Reflector on p-Type GaN Using Ni/Au/W/Ag Ohmic Contact

We investigate the properties of a Ni/Au/W/Ag reflector layer deposited on a p-GaN layer for use in high efficiency GaN flip-chip light-emitting diodes (LEDs) or vertical LEDs. The FCLEDs fabricated with Ni/Au/W/Ag contact showed good current-voltage characteristic and an enhanced the optical output power compared to those fabricated with Ni/Au/Ag contact due to the high reflectivity, smooth surface after annealing, and good Ohmic property of Ni/Au/W/Ag. These results clearly indicate that a Ni/Au/W/Ag contact on p-GaN constitutes a promising reflector and Ohmic scheme for achieving high-brightness LEDs. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.026206esl] All rights reserved.