Electrical properties of (Ca,Sr)Bi₄Ti₄O₁₅ thin films fabricated using a chemical solution deposition method

Thin films of calcium-strontium bismuth titanate (Ca_1-xSr_x)Bi₄Ti₄O₁₅ solid solution were fabricated on (111)Pt/Ti/SiO₂/(100)Si substrates by a chemical-solution deposition (CSD) technique. These films had x = 0-1.00 and consisted of a polycrystalline structure with random orientation of the bismuth layer-structured ferroelectric (BLSF) crystal (m = 4). The relative dielectric constants of (Ca_1-xSr_x)Bi₄Ti₄O₁₅ films were enhanced from 40 to 220 with increasing x; these values did not vary significantly with changes in the measuring frequency and the bias field. The temperature coefficient of the relative dielectric constant at around room temperature became larger with increasing x from 0 to 1.00; the change in the dielectric constant of these films between 30-100°C increased from 2% to 15%.