Structural and Dielectric Properties of Ba(Ti_1-xSn_x)O₃ Thin Films

Abstract

Close correlation between the dielectric constant and the degree of preferential (111) orientation is found for Ba(Ti 0.85 Sn 0.15 )O 3 ( BTS 15 ) solid-solution thin films deposited on a Pt/Ti/SiO 2 /Si(100) substrate by pulsed laser deposition. It is shown that substrate temperature is the principal factor which determines orientation and crystalline quality of the films. Substrate temperatures higher than 700° C are required to achieve (111) orientation with good crystalline quality. BTS 15 films with strong (111) orientation have large dielectric constant which reaches 2500 at 22° C. These films exhibit a D - E hysteresis loop, but small remanent polarization of 0.89 µ C/cm 2 and coercive field of 3.2 kV/cm are obtained at 18° C. Films having the composition with lower Sn ratio exhibit larger remanent polarization. Causal relationships among the dominant film orientation, crystalline quality and dielectric constant are discussed.