Structure, Microstructure, and Dielectric Response of Polycrystalline Sr1-xZnxTiO3 Thin Films

Abstract

In a view of the research interest in the high-permittivity materials, continuous enhancement of the dielectric permittivity ε′ with Zn content was reported for conventionally prepared Sr1-xZnxTiO3 ceramics with x up to 0.009, limited by the solubility of Zn on Sr site. Here, we use a sol-gel technique and a relatively low annealing temperature of 750 °C to prepare monophasic Sr1-xZnxTiO3 thin films with higher x of 0.01, 0.05, and 0.10 on Pt/TiO2/SiO2/Si substrates. The incorporation of Zn on the Sr site is confirmed by the decrease of the lattice parameter, while the presence of Zn in the films is proven by energy dispersive spectroscopy. The film thickness is found to be ~330 nm by scanning electron microscopy, while the average grain size of 86–145 nm and roughness of 0.88–2.58 nm are defined using atomic force microscopy. ε′ measured on the films down to 10 K shows a decreasing trend with Zn content in contrast to that for weakly doped Sr1-xZnxTiO3 ceramics. At the same time, the temperature dependence of the dissipation factor tanδ reveals a peak, which intensity and temperature increase with Zn content.