Thermally Stable Sr₂RuO₄ Electrode for Oxide Heterostructures

The use of thermally stable Sr 2 RuO 4 electrodes in high-temperature synthesis of oxide heterostructures was investigated. Atomically smooth Sr 2 RuO 4 thin films were grown on SrTiO 3 (001) substrates by pulsed laser deposition and used as a bottom electrode for ferroelectric BaTiO 3 capacitors grown at temperatures of up to 1000 °C. The thermal stability of Sr 2 RuO 4 electrodes was verified by structural and electrical measurements of the ferroelectric BaTiO 3 films. The best growth temperature for the BaTiO 3 films was found to be 900 °C, exhibiting the largest spontaneous polarization, dielectric constant, and pyroelectric response. We conclude that Sr 2 RuO 4 films are suitable for use as thermally stable electrodes in heterostructures synthesized at temperatures up to at least 1000 °C and oxygen pressures from 10 –6 to 10 –1 Torr. This range of growth film conditions is much wider than that for other common oxide electrode materials such as SrRuO 3, widening the available process window for optimizing the performance of oxide electronic devices.