Tunability Of Films Research Articles

Enhanced electric field tunable dielectric properties of Ba(Sn0.15Ti0.85)O3 thin films

Highly (100)-oriented barium stannate titanate Ba(Sn0.15Ti0.85)O3 (BTS) thin films were deposited on SrTiO3 (STO) and Nb doped SrTiO3 (NSTO) single-crystal substrates through sol-gel process, respectively. Coplanar capacitance and parallel plate capacitance structure configurations were formed by preparing interdigital electrodes (IDEs) and parallel plate electrodes (PPEs) on BTS thin film. The tunability of films with IDE was 45.54%, while the tunability of films with PPE was only 11.54% at the frequency of 1 MHz with an applied electric field of 80 kV/cm. This result showed that the tunability in the a-b plane contributes markedly to the measurements obtained with the IDE.

Orientation control and dielectric properties of sol–gel deposited Ba(Sn 0.15Ti 0.85)O 3 thin films grown on Pt/Ti/SiO 2/Si substrates

Ba(Sn 0.15Ti 0.85)O 3 (BTS) thin films were grown on Pt(2 0 0)/Ti/SiO 2/Si(1 0 0) and Pt(1 1 1)/Ti/SiO 2/Si(1 0 0) substrates by a sol–gel processing technique, respectively. The dependence of microstructure and dielectric properties on film orientation has been studied. The BTS thin films directly grown on Pt(2 0 0)/Ti/SiO 2/Si substrates exhibited highly (1 0 0) and (1 1 0) preferred orientation depending upon concentration of the precursor solution. The BTS thin films directly grown on Pt(1 1 1)/Ti/SiO 2/Si substrates exhibited highly (1 1 1) preferred orientation. The dielectric constant of the BTS films with (1 0 0), (1 1 0) and (1 1 1) preferred orientation was 485, 240 and 510, respectively, measured at a frequency of 1 MHz and at room temperature. The tunability of films with (1 0 0) preferred orientation was 36.10%, which was higher than that of BTS thin films with (1 1 0) and (1 1 1) preferred orientation at the frequency of 1 MHz with an applied electric field of 200 kV/cm. This work clearly reveals the microstructure and dielectric properties of BTS thin films exhibited a strong sensitivity to crystal orientation.

Phase diagram and dielectric behavior of Ba0.6Sr0.4TiO3 thin films grown on orthorhombic substrates

Abstract Using Landau–Devonshire (LD)-type phenomenological model, we investigate the phase diagrams and dielectric behaviors of single-domain single-crystal Ba 0.6 Sr 0.4 TiO 3 films deposited on orthorhombic substrates. An anisotropic strain factor is introduced to quantitatively calculate the effects of anisotropic in-plane misfit strains. Investigation indicates that anisotropic strains play a crucial role on formation of stable ferroelectric phases and dielectric properties. The anisotropic strains induce tetragonal phases which only contain one in-plane spontaneous polarization component. These phases do not exist in BST films of the same composition under isotropic strains. Moreover, permittivity and tunability of films can reach to maximum when the corresponding spontaneous polarization component disappears at the boundaries of structural phase transition.