Low transparent Pt ohmic contact on p-type GaN by surface treatment using aqua regia

A low transparent ohmic contact on p-type GaN has been achieved through the deposition of Pt on p-type GaN treated using boiling aqua regia. The contact resistivity was decreased from 4.7×10-1 to 1.4×10-4 Ωcm² by the surface treatment. The drastic reduction in contact resistivity originates from both the removal of surface oxides by the boiling aqua regia and the high work function of Pt. The surface treatment plays a role in reducing the barrier height for holes at the Pt/p-type GaN interface, leading to good ohmic contacts on p-type GaN