Interface Properties between Ni and p-GaN Studied by Photoemission Spectroscopy

Interface properties between p-GaN and Ni were investigated by vacuum ultra violet photoemission spectroscopy and atomic force microscopy. It was found that residual oxide on the GaN surface was removed by Ni deposition and subsequent annealing, and the layered Ni became an island-like shape with annealing in O2 ambient. Such annealing effects result in the direct contact of Au with atomically clean GaN in a Au/Ni/p-GaN structure. On the basis of these results, it can be concluded that the cleaning effect of Ni and island formation of oxidized Ni may play an important role in forming an ohmic contact to p-GaN.