High-Quality Cu-Ni Solid Solution/Ag Ohmic Contacts for Flip-Chip Light-Emitting Diodes

Very low resistance and reflective Cu-Ni solid solution/Ag ohmic contacts to p-GaN for flip-chip light-emitting diodes (LEDs) were investigated. The Cu-Ni solid solution/Ag contacts produce specific contact resistance of 10 − 5 to 10 − 6 Ω cm 2 when annealed at 450 and 550°C for 1 min in air. LEDs fabricated with the annealed Cu-Ni solid solution/Ag contact layers give lower forward-bias voltages of 3.18-3.20 V at 20 mA. The light output power of LEDs with the Cu-Ni solid solution/Ag contact layer is higher than that of the Cu/Ag contact LEDs.