Nanoparticle Embedded p-Type Electrodes for GaN-Based Flip-Chip Light Emitting Diodes

We have investigated high-quality ohmic contacts for flip-chip light emitting diodes using Zn–Ni nanoparticles/Ag schemes. The Zn–Ni nanoparticles/Ag contacts produce specific contact resistances of 10⁻⁵–10⁻⁶ Ωcm² when annealed at temperatures of 330–530 °C for 1 min in air ambient, which are much better than those obtained from the Ag contacts. It is shown that blue InGaN/GaN multi-quantum well light emitting diodes fabricated with the annealed Zn–Ni nanoparticles/Ag contacts give much lower forward-bias voltages at 20 mA compared with those of the multi-quantum well light emitting diodes made with the as-deposited Ag contacts. It is further presented that the multi-quantum well light emitting diodes made with the Zn–Ni nanoparticles/Ag contacts show similar output power compared to those fabricated with the Ag contact layers.