FABRICATION OF Sr1-xBaxBi4Ti4O15 THIN FILMS FOR PIEZOELECTRIC PRESSURE SENSORS

Abstract

This paper reports the fabrication of Strontium Barium Bismuth Titanate Sr_1-xBa_xBi₄Ti₄O₁₅ (SBBT) thin films for piezoelectric pressure sensors. The SBBT films and capacitance devices with structure of Al/TiO₂/SBBT/TiO₂/SiO₂/Si were fabricated using sol-gel technique. The microstructure of SBBT thin films has been systematically studied in as-prepared (un-annealed) condition as well as after annealing at 500 °C for 2 mins. The general trend seems to indicate that the annealed samples showed better piezoelectric properties. X-ray diffraction patterns reveal changes of crystalline structure after annealing. Another important parameter is dielectric constant, which is found toward higher value after annealing. For the sensor device measurement, the SBBT thin film pressure sensors were tested by pneumatic loading method at pressure range between 0 to 450 kPa. It was found that the sensor was sensitive to applied pressure and the response recovered back when the pressure removed. An annealed pressure sensor demonstrates better sensitivity and repeatability compared to un-annealed. The results indicated that the sensor performance was affected by the structure of the film. A crystalline structure gives an optimum response towards pneumatic pressure. The correlation between annealing process with structure of SBBT and piezoelectric property will be discussed.