Preparation of (020)-oriented BaTi ₂O ₅ thick films and their dielectric responses

Barium dititanate (BaTi ₂O ₅) thick films were prepared on a Pt-coated Si substrate by laser chemical vapor deposition, and ac electric responses of (020)-oriented BaTi ₂O ₅ films were investigated using several equivalent electric circuit models. BaTi ₂O ₅ films in a single phase were obtained at a Ti/Ba molar ratio (m _Ti/Ba) of 1.72-1.74 and deposition temperature (T _dep) of 908-1065K as well as m _Ti/Ba=1.95 and T _dep=914-953K. (020)-oriented BaTi ₂O ₅ films were obtained at m _Ti/Ba=1.72-1.74 and T _dep=989-1051K. BaTi ₂O ₅ films had columnar grains, and the deposition rate reached 93μmh ^-1. The maximum relative permittivity of the (020)-oriented BaTi ₂O ₅ film prepared at T _dep=989K was 653 at 759K. The model of an equivalent circuit involving a parallel combination of a resistor, a capacitor, and a constant phase element well fitted the frequency dependence of the interrelated ac electrical responses of the impedance, electric modulus, and admittance of (020)-oriented BaTi ₂O ₅ films.