Effect of in-plane ordering on dielectric properties of highly {111}-oriented bismuth–zinc–niobate thin films

Bi 1.5-x Zn 0.92-y Nb 1.5 O 6.92-δ (BZN) thin films were grown by pulsed laser deposition on two different Pt-covered substrates, namely textured {111}Pt/TiO 2 /SiO 2 /(100)Si substrate (Pt/Si) and epitaxial {111}Pt/R-plane sapphire substrate (Pt/sapphire). In both cases, the BZN films present {111} and {100} out-of-plane orientations, in relative ratios of 65/35 on Pt/Si, and 80/20 on Pt/sapphire, respectively. The film grown on Pt/Si is textured, while the film deposited on Pt/sapphire presents epitaxial-like relationships with the substrate, for both out-of-plane orientations. Dielectric measurements were performed on both types of thin films, using Pt/BZN/Pt planar capacitor structures. The BZN/Pt/sapphire film presents higher dielectric constant (245 at 100 kHz) and higher tunability (12 % at 600 kV/cm) than the BZN/Pt/Si film (200; 6 %), while the dielectric losses values are nearly the same (~ 0.05).