Low-resistance Pt/Ni/Au ohmic contacts to p-type GaN

We report on a Pt (20 nm) Ni (30 nm)/Au (80 nm) metallization scheme for low-resistance ohmic contacts to the moderately doped p-type GaN:Mg (3×1017 cm−3). Both as-deposited and annealed Pt/Ni/Au contacts on p-GaN exhibit linear current–voltage characteristics, showing that a high-quality ohmic contact is formed. The Pt/Ni/Au scheme shows the specific contact resistance of 5.1×10−4 Ω cm2 when annealed at 350 °C for 1 min in a flowing N2 atmosphere.