Ohmic contact to p-type GaN using a novel Ni/Cu scheme

In this paper, formation of low resistance ohmic contact to p-type GaN using an alloy of Ni/Cu was reported. The Mg doped samples were deposited with Ni (20nm)/Cu (20nm) and then annealed in nitrogen ambient at different annealing temperatures ranging from 400 to 700 °C. A good ohmic contact with a specific contact resistance of 1.31 × 10 ^-4 Ω cm ² was obtained when the sample was annealed at 600 °C for 30 s. The decrease of specific contact resistance is attributed to the increased contact area and local electric field, and extraction of hydrogen from the p-type GaN.