Low-resistant and high-transparent Ru/Ni ohmic contact on p-type GaN

We report a low-resistant and high-transparent Ru-based ohmic contact on p-type GaN through oxidation annealing under O-2 atmosphere. A low resistivity of 4.5x10(-5) Omega cm(2) and high light transmittance (84.6%) were simultaneously obtained from oxidized Ru (50 Angstrom)/Ni (50 Angstrom) contact. The RuO2 formed on p-type GaN played a role in reducing the effective Schottky barrier height for injection of holes and NiO layer produced on the RuO2 acted as a diffusion barrier for the outdiffusion of released Ga and N atoms, resulting in the reduction of the contact resistivity as well as the enhancement of light transmission. (C) 2002 American Institute of Physics.open112731sciescopu