High-Throughput Synthesis and Characterization of (BaxSr1–x)1+yTi1–yO3−δ and (BaxSr1–x)1+yTi1–yO3–zNz Perovskite Thin Films

Abstract

Thin films of (BaxSr1–x)1+yTi1–y and Zr, Gd codoped (BaxSr1–x)1+yTi1–y were deposited on platinized sapphire substrates at 640 °C under constant flux of atomic oxygen or a mixture of atomic oxygen and nitrogen to synthesize perovskites of (BaxSr1–x)1+yTi1–yO3?? (also referred to as BSTO), (BaxSr1–x)1+yTi1–yO3–zNz (also referred to as BSTON), and Zr, Gd codoped (BaxSr1–x)1+yTi1–yO3–zNz. Structural characterization was done via XRD and XPS, and electrical characterization was done via LCR (dielectric properties and tunability under DC bias) and P–E measurements. Although the levels of nitrogen incorporated within the perovskite structure appear to be very low as determined by XPS analysis, definite improvements in dielectric properties and tunability have been achieved by synthesis of the BSTON oxynitride films. For a composition of Ba0.8Sr0.2TiO3–zNz an improvement by a factor of 1.72 for tunability and 1.44 for relative permittivity has been observed between the oxide and the oxynitride. The oxynitride achieved a tunability ratio of 6.78 to 1 (close to 7:1) under an applied electrical field of 34 kV/mm. The high throughput approach allowed us to highlight a compositional shift for the material with the best dielectric properties when comparing the oxide with the oxynitride thin films. Effects of codoping the perovskite structure with Zr and Gd have also been investigated and although the tunability and dielectric constant of the thin films were not improved, some improvements in dielectric losses were observed, along with a superparaelectric state as observed by P–E hysteresis measurements.