Sol-gel derived barium strontium titanate thin films for uncooled infrared detector array applications

Abstract

Columnar Ba_0.8Sr_0.2TiO₃ films with a grain size of 100 to 200 nm have been obtained from a 0.05M precursor solution. Electrical measurements indicated these films showed a pyroelectric coefficient of 4.1 × 10^-4 C/m²K at room temperature, and a leakage current of 1.42 × 10^-7 A/cm² under 100 kV/cm electrical field. The Ba_0.8Sr_0.2TiO₃ films have been used for fabricating a 1 × 16 elements infrared detector linear array with a bulk micromachining technique. The array pixels with a sensitive area of 500 × 300 μm² have a detectivity of 2.3 × 10⁸ cmHz^½W^-1 at 23°C and 35 Hz. By using these infrared detector arrays, thermal images were successfully obtained at room temperature. These results indicate the sol-gel derived Ba_0.8Sr_0.2TiO₃ films from a 0.05M precursor solution are suitable for uncooled infrared detector array applications.