Dielectric response of BaZrO₃/BaTiO₃ and SrTiO₃/BaZrO₃ superlattices

Abstract

Dielectric materials with high tunability, low loss, and desired range of permittivity are an attractive class of materials for a variety of applications in microwave components such as tunable filters, phase shifters, antennas, etc. In this article, we have investigated the low frequency dielectric properties of BaZrO₃/BaTiO₃ and SrTiO₃/BaZrO₃ superlattices of varying modulation periods for the potential application toward electrically tunable devices. The dielectric response of the superlattices as a function of temperature revealed remarkable stability for both types of superlattices, with no observed dielectric anomalies within that range. Dielectric losses were also nominally low with minimal variation within the measured temperature range. Sufficiently high tunability of ~40% was observed for the BaZrO₃/BaTiO₃ superlattices at the lowest individual layer thicknesses. In comparison, the SrTiO₃/BaZrO₃ superlattices showed a minimum tunability for lowest period structures. It showed maximum tunability of ~20% at 10 kHz and room temperature at an intermediate dimension of 3.85 nm periodicity superlattice. The tunability value degraded with increasing as well as decreasing periodicities for the SrTiO₃/BaZrO₃ superlattices. The dielectric response has been explained on the basis of size effects, interlayer coupling between dissimilar materials, domain contribution, and depolarizing electric fields.