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 flat surface and uniform thickness is obtained by spin coating in N₂ atmosphere which avoid moisture. The BTS₁₅ film has a perovskite phase and is random-oriented, with strong (110) orientation. It is also found that crystalline structure is cubic at 24°C with lattice constant of 4.01 Å, and grain size of about 30 nm estimated by Scherrer equation and SEM image. From P-E hysteresis loop at 20°C, the polarization at E = 0 and electric field at P = 0 are 1.07 μC/cm² and 24.0 kV/cm, respectively. It is observed that dielectric constant decreases monotonously from about 830 to 630 with increasing temperature ranging from 20 to 50°C. Finally, it is found that the BTS₁₅ thin film shows a sufficient ferroelectricity and is an attractive material for the functional ferroelectric devices, such as thermal-type infrared sensor.