Phase Formation and Morphology in Nickel and Nickel/Gold Contacts to Gallium Nitride

Metallurgical reactions between Ni and GaN have been explored at temperatures between 400 and 900 °C in N 2 , Ar, and forming gas. A trend of increasing Ga content in the reacted films was observed with increasing temperature. The reactions are consistent with the thermodynamics of the Ni-Ga-N system. Changes in the film morphology on annealing were also examined. Metal island formation and a corresponding deep, non-uniform metal penetration into GaN were observed at high temperatures. The relevance of the observed nature of phase formation and morphology in these thin films to electrical properties of Ni/GaN and Au/Ni/GaN contacts is also considered.