Reaction between GaN and Metallic Deposition Films

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. Ni 5 Ga 3 is formed at the interface by the post-deposition anneal. As the other product of the interfacial reaction, N 2 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.

Effect of interfacial reaction on electrical conduction across the interface between n-type gallium nitride and contact materials

“…Although the relation is different from that observed in previous reports [10,13], the existence of such a relation implies the formation of TiN adjacent to GaN. The electric conduction profile between two 1.0-mm-distant contact films on Sample 1 is shown in Figure 2.…”

“…Formation of TiN by interfacial reaction between GaN and Ti generates nitrogen vacancies in GaN, which work as donors at an energy level close to the conduction band edge of GaN. Therefore, TiN is formed adjacent to GaN generally by interfacial reaction between GaN and multilayered metallic film containing Ti layer [7][8][9][10]. However, this method has a problem.…”

“…However, this method has a problem. Interlayer reactions during heat treatment form several intermetallic compounds in the film [10]. The compounds have high electric resistances and brittle nature.…”

Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes

“…GaN and Pd are divided by Au-Ni clusters. Unlike [18], no NixGay or NixNy phases were observed. It is well established that Ga-face p-GaN exhibits robust chemical resistance [19].…”