Fabrication and Characterization of Pyroelectric Ba_0.8Sr_0.2TiO₃ Thin Films by a Sol-Gel Process

A sol-gel process was used to prepare pyroelectric Ba_0.8Sr_0.2TiO₃ thin films with large columnar grains (100-200 nm in diameter) on Pt/Ti/SiO₂/Si substrates, via using a 0.05M solution precursor. The relationship between dielectric constant and temperature (ε_r-T) showed two distinctive phase transitions in the Ba_0.8Sr_0.2TiO₃ thin films. Both the remnant polarization and the coercive field decreased as the temperature increased from -73°C to 40°C. Its low dissipation factor (tan δ = 2.6%) and high pyroelectric coefficient (p = 4.6 × 10^-4 C·(m₂·K)^-1 at 33°C), together with its good insulating properties, made the prepared Ba_0.8Sr_0.2TiO₃ thin films promising for use in uncooled infrared detectors and thermal imaging applications.