The temperature dependent diffusion and epitaxial behavior of oxidized Au/Ni/p-GaN ohmic contact were studied with Rutherford back-scattering spectroscopy/channeling and synchrotron X-ray diffraction. It was found that the Au diffused to the surface of p-GaN to form an epitaxial structure on p-GaN after annealing at 450C. At the same time, the O diffused to the metal–semiconductor interface and formed NiO. Both of them were suggested to be responsible for a sharp decrease in the specific contact resistance (ρc) at 450C. At 500C, the epitaxial structure of Au develops further and the O also diffused deeper into the interface. As a result, the ρc reached the lowest value at this temperature. However, when the annealing temperature reached 600C, part or all of the interfacial NiO was detached from the p-GaN and diffused out, which caused the ρc to increase greatly.

Temperature Dependent Diffusion and Epitaxial Behavior of Oxidized Au/Ni/p-GaN Ohmic Contact. C.Y.Hu, Z.X.Qin, Z.X.Feng, Z.Z.Chen, Z.B.Ding, Z.J.Yang, T.J.Yu, X.D.Hu, S.D.Yao, G.Y.Zhang: Materials Science and Engineering B, 2006, 128[1-3], 37-43