Broadband dielectric spectroscopy of BiFeO3 thin film up to Ku band frequency

Abstract

BiFeO3 (BFO) thin film nano-structures were grown by pulsed laser deposition (PLD) and their structural and dielectric responses were investigated over a broad frequency band of 10 kHz < f < 15 GHz. An on-chip reflection measurement technique was used, followed by S-parameter based dielectric property extraction for microwave evaluation. The leakage current behaviour was investigated under applied electric field up to 500 kV cm−1. The phase pure polycrystalline film exhibited low leakage current and a very high dielectric constant of 169.785 at 10 MHz and 149 at 15 GHz. The dielectric losses of the film were low. Both dielectric permittivity and loss tangents were found to be nearly frequency non-dispersive over the investigation range and no dielectric relaxation was observed up to 15 GHz. These findings demonstrate that a BFO film with such properties is found to be suitable for tuneable thin film bulk acoustic wave resonators (TFBARs), microwave absorbers and tuneable microwave devices at room temperature.