Preparation of ferroelectric Ba(Ti0.85Sn0.15)O3 thin films by metal-organic decomposition

Ferroelectric Ba(Ti_0.85Sn_0.15)O₃ (BTS₁₅) thin film is newly prepared on the Pt/Ti/SiO₂/Si substrate by metal-organic decomposition. The firing condition is determined by thermogravimetric and differential thermal analysis. The BTS₁₅ thin film with a flat surface and uniform thickness is obtained by spin coating in N₂ atmosphere that avoids moisture. The BTS₁₅ film has a perovskite phase and a preferential [110] texture. It is also found that the crystalline structure is cubic at 24°C with a lattice constant of 4.01 Å, and a grain size of about 30 nm was estimated by Scherrer equation and SEM image. From P-E hysteresis loop at 20°C, the polarization at E=0 and the electric field at P=0 are found to be 1.07 μC/cm² and 24.0 kV/cm, respectively. It is observed that the dielectric constant decreases monotonously from about 830 to 630 with increasing temperature ranging from 20°C to 50°C. Finally, it is found that the BTS₁₅ thin film shows a sufficient ferroelectricity and is an attractive material for functional ferroelectric devices, such as thermal-type infrared sensors.