Reactive co-sputtering of ternary Au-Ta-O films with tunable electrical resistivity

Heavy-metal-based films with high electrical resistivity are needed for hohlraums for magnetically assisted inertial confinement fusion. Here, we study ternary Au-Ta-O films deposited by reactive direct-current magnetron co-sputtering from elemental Au and Ta targets in an oxy-gen containing atmosphere. By varying the O content, the electrical resistivity of films can be tuned in a wide range of similar to 100-40 000 mu omega cm. With increasing O content, a drastic increase in resistivity occurs at -45 at. % of O, separating regimes with two different dominant conduction mechanisms attributed to metallic conduction through the Au-Ta alloy matrix (for >= 45 at. % of O) and tunneling across insulating Ta2O5 layers separating conducting islands (for <= 45 at. % of O). Post-deposition annealing at 300 degrees C leads to the segregation of Au into -50-nm islands, sharply decreasing the resistivity for films with >= 45 at. % of O but not for the metal-like films with lower O content. Published under an exclusive license by AIP Publishing.

Automated summary

By adjusting the oxygen content, we studied the electrical resistivity characteristics and the transition of conduction mechanism of Au-Ta-O films, providing a new thin film material alternative for hohlraums in magnetically assisted inertial confinement fusion.