Influence of deposition temperature on microstructure and electrical properties of modified (Ba, Sr)TiO3 ferroelectric thin films

Modified Ba0.67Sr0.33TiO3 (BST) thin films were deposited on Pt/Ti/SiO2/Si substrates using RF magnetron sputtering. By optimizing the deposition temperature (Td), the dielectric and ferroelectric properties of BST films were improved. The onset of crystallization of the BST films was observed at about 600 °C, beyond which there was an increase in grain size with further increasing Td up to 700 °C. The better crystallized film deposited at 700 °C with a thickness of 670 nm shows a polycrystalline and dense structure, a dielectric constant (εrεr)=953.40 (at 100 kHz), and a remanent polarization (2Pr)=23.87 μC/cm2. The dielectric tunability at 1 MHz increases as Td increases, and reaches the highest value of 55.40% for an applied field of 770 kV/cm at the highest Td of 700 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electric performance analysis also indicate that the deposition temperature during growth strongly affects the microstructure of BST films. This in turn influences the dielectric, ferroelectric and tunable behavior of BST films.