Thermally-stable low-resistance Ti/Al/Mo/Au multilayer ohmic contacts on n–GaN

A metallization scheme consisting of Ti/Al/Mo/Au with excellent edge acuity has been developed for obtaining low-resistance ohmic contacts to $\mathrm{n–}\mathrm{GaN}.$ Excellent ohmic characteristics with a specific contact resistivity as low as ${\text{4.7×10}}^{\text{−7}}\mathrm{ \Omega -}{\mathrm{cm}}^2$ were obtained by rapid thermal annealing of evaporated Ti/Al/Mo/Au at 850 °C for 30 sec in a ${\mathrm{N}}_2$ ambient. Additionally, no degradation in specific contact resistivity was observed for these contacts subjected to long-term annealing at 500 °C for 360 h.