Effect of internal interface layer on dielectric properties of doped Ba0.6Sr0.4TiO3 thin films and its simulation in filters

Effect of the internal interface layer on the dielectric properties of doped Ba0.6Sr0.4TiO3 (BST) films and their simulation research in filters. Based on the interfacial effect in the multi-layer ferroelectric thin film, a different number of internal interface layers was proposed and introduced into the Ba0.6Sr0.4TiO3 thin film. First, Ba0.6Sr0.4Ti0.99Zn0.01O3 (ZBST) sol and Ba0.6Sr0.4Ti0.99Mg0.01O3 (MBST) sols were prepared using the sol-gel method. Ba0.6Sr0.4Ti0.99Zn0.01O3/Ba0.6Sr0.4Ti0.99Mg0.01O3/Ba0.6Sr0.4Ti0.99Zn0.01O3 thin films with 2 layer internal interface layer, 4 layer internal interface layer and 8 layer internal interface layer were designed and prepared (I2, I4, I8). The effects of the internal interface layer on the structure, morphology, dielectric properties, and leakage current behavior of the films were studied. The results showed that all the films were of the cubic perovskite BST phase and had the strongest diffraction peak in the (110) crystal plane. The surface composition of the film was uniform, and there was no cracked layer. When the bias of the applied DC field was 600 kV cm(-1), the high-quality factor values of the I8 thin film at 10 MHz and 100 kHz were 111.3 and 108.6, respectively. The introduction of the internal interface layer changed the leakage current of the Ba0.6Sr0.4TiO3 thin film, and the I8 thin film exhibited the minimum leakage current density. The I8 thin-film capacitor was used as the tunable element to design a fourth-step 'tapped' complementary bandpass filter. When the permittivity was reduced from 500 to 191, the central frequency-tunable rate of the filter was 5.7%.