Abstract
The interfacial microstructures of two typical contact films for gallium nitride (GaN) have been investigated by transmission electron microscopy. One is a 300-nm-thick Ni single-layer deposited on p-type GaN and then annealed at 873 K. Ni5Ga3 is formed at the interface by the post-deposition anneal. As the other product of the interfacial reaction, N2 voids are formed bulging to the Ni-side. The other contact film consists of four layers: Ti, Al, Ni, and Au, at the initial state. By annealing at 873 K for 300 s, the reactions proceed between GaN and Ti and also among the layers. The reaction at the GaN/Ti interface forms a thin layer of TiN adjacent to GaN. The layered structure disappears completely due to the interlayer reaction and subsequent growth of the reaction product grains.
