Anti-diffusion Barriers for Gold-Based Metallization to GaN

We propose a new metallization scheme to p-GaN, where thin-film transition metal nitrides have been applied to improve thermal stability of gold-based metallization. In this metallization scheme the Pd/Au bilayer was used to form low-resistivity ohmic contact to p-GaN, while Ta-Si-N, Ti-Si-N, and Ti-W-N anti-diffusion barriers were used to protect contact metallization from interaction with Au overlayer. We present the details of optimization of process parameters of barrier layer fabrication and show that Ta 0.34 Si 0.25 Ni 0.41 and Ti 0.26 Si 0.0.17 Ni 0.57 thin films fabricated by reactive magnetron sputtering show excellent barrier properties under high temperature stress.