Ir/Ag reflector for high-performance GaN-based near UV light emitting diodes

We report on the formation of reflective and low resistance Ag-based contacts to p-GaN using Ir interlayers for GaN-based near UV flip-chip light emitting diodes (FCLEDs). The as-deposited Ir/Ag contacts give non-linear current-voltage (I-V) behaviors. However, the contacts become ohmic with specific contact resistance of ∼10^-4 Ω cm² when annealed at temperatures 330-530 °C for 1 min in air. The 530 °C-annealed Ir/Ag contacts give a reflectance of ∼75% at a wavelength of 405 nm, which is somewhat higher than that (∼71%) of annealed single Ag contacts. It is also shown that the output power of the LEDs made with the annealed Ir/Ag contact is higher than that with the annealed single Ag contact.