Nano-dot addition effect on the electrical properties of Ni contacts to p-type GaN

The correlations between the electrical behaviors of Ni contacts on p-GaN and the insertion of metal nano-dots at the Ni/GaN interfaces have been investigated. The Pt, Au, and Ti nano-dots directly deposited on p-GaN using the anodic porous alumina membrane mask by electron beam evaporation. It is shown that the samples with the inserted nano-dots exhibit better electrical behaviors compared with those without the nano-dots. The improvement of the electrical behaviors is explained in terms of the difference of the Schottky barrier heights between the Ni film and the metal nano-dots, and the enhanced electrical field at the Ni/GaN interfaces due to the presence of the nano-dots. Based on experimental and theoretical results, the possible mechanisms for the improved electrical behaviors is discussed.