High Capacitance Density and Thermal Stability in Strontium

Magnetron sputtering allows for the accurate estimation of film thickness. Strontium titanate (STO) thin films were deposited on Nb-doped STO substrates using radiofrequency magnetron sputtering technology. The microstructures and dielectric properties of STO thin films were investigated. X-ray diffraction (XRD) analysis indicates that uniform polycrystalline STO films were obtained after thermal annealing at 650 °C. The films exhibit a significant correlation between thickness, annealing temperature, and breakdown field strength. The optimal film with a thickness of 1150 nm achieves a capacitance density of 1688 pF/mm² and a breakdown field strength of 270 kV/mm. Additionally, STO films annealed at 650 °C maintained their capacitance value within ±15% across a temperature range of -55 °C to 125 °C. These results highlight the potential of STO thin films for high-performance capacitor applications.