Pyroelectric properties in sol–gel derived barium strontium titanate thin films using a highly diluted precursor solution

The pyroelectric coefficient and pyroelectric infrared response in the sol–gel derived ${\mathrm{Ba}}_{\mathrm{0.8}}{\mathrm{Sr}}_{\mathrm{0.2}}{\mathrm{TiO}}_{\mathrm{3}}$ thin films have been studied for possible infrared detector applications. The measured pyroelectric coefficient is larger than ${\text{3.1×10}}^{\text{−4}} {\mathrm{C/m}}^{\mathrm{2}}\mathrm{ K}$ at temperatures ranging from 10 to $\text{26\hspace{0.05em}°}\mathrm{C}$ and reaches the maximum value of ${\text{4.1×10}}^{\text{−4}} {\mathrm{C/m}}^{\mathrm{2}}\mathrm{ K}$ at $\text{16\hspace{0.05em}°}\mathrm{C}.$ The infrared detectivity of ${\text{4.6×10}}^6 {\mathrm{cm Hz}}^{\mathrm{1/2}}{\mathrm{ W}}^{\mathrm{-1}}$ has been obtained at $\text{19\hspace{0.05em}°}\mathrm{C}$ and 10 Hz in the ${\mathrm{Ba}}_{\mathrm{0.8}}{\mathrm{Sr}}_{\mathrm{0.2}}{\mathrm{TiO}}_{\mathrm{3}}$ films deposited on thick (500 μm) platinum coated silicon substrates. The better infrared response can be expected by the improvement in the thermal isolation of pyroelectric element and the electrode materials.