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

Abstract

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 oxygen containing atmosphere. By varying the O content, the electrical resistivity of films can be tuned in a wide range of [Formula: see text] [Formula: see text] cm. With increasing O content, a drastic increase in resistivity occurs at [Formula: see text] at. % of O, separating regimes with two different dominant conduction mechanisms attributed to metallic conduction through the Au–Ta alloy matrix (for [Formula: see text] at. % of O) and tunneling across insulating Ta2O5 layers separating conducting islands (for [Formula: see text] at. % of O). Post-deposition annealing at 300 °C leads to the segregation of Au into [Formula: see text]-nm islands, sharply decreasing the resistivity for films with [Formula: see text] at. % of O but not for the metal-like films with lower O content.