Preparation of ferroelectric Ba(Ti/sub 0.85/Sn/sub 0.15/)O/sub 3/ thin films by metal-organic decomposition

Abstract

Ferroelectric Ba(Ti/sub 0.85/Sn/sub 0.15/)O/sub 3/ (BTS/sub 15/) thin film is newly prepared on the Pt/Ti/SiO/sub 2//Si substrate by Metal-Organic Decomposition. The firing condition is determined by thermogravimetric and differential thermal analysis. The BTS/sub 15/ thin film with flat surface and uniform thickness is obtained by spin coating in N/sub 2/ atmosphere which avoid moisture. The BTS/sub 15/ film has a perovskite phase and is random-oriented, with strong (110) orientation. It is also found that crystalline structure is cubic at 24/spl deg/C with lattice constant of 4.01 /spl Aring/, and grain size of about 30 nm estimated by Scherrer equation and SEM image. From P-E hysteresis loop at 20/spl deg/C, the polarization at E = 0 and electric field at P = 0 are 1.07 /spl mu/C/cm/sup 2/ 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/spl deg/C. Finally, it is found that the BTS/sub 15/ thin film shows a sufficient ferroelectricity and is an attractive material for the functional ferroelectric devices, such as thermal-type infrared sensor.