Niobium Zinc Bismuth Bzn Films And Dielectric Tunable Performance

In recent years, microwave dielectric materials have attracted attention as regards particular application such as microwave functional devices. As a novel potential material for microwave functional devices, bismuth zinc niobates with the pyrochlore structure have drawn wide interest for the field-tunable permittivity and low loss.In this work, BZN thin films have been deposited using RF magnetron sputtering. The effect of deposition parameters on the composition, microstructure and dielectric properties of BZN thin films have been investigated. Main research results are summarized as follows:1. Thin films were deposited by RF magnetron sputtering on Au/Si substrates. The deposition parameters were: the RF power of 100W, the temperature of substrates of 300℃, and a post-deposition annealing of 1 min at 700℃to crystallize the films. X-ray powder diffraction detected only the cubic pyrochlore phase.2. Au/BZN/Au structure capacitor was prepared, Influence of the different compositon, electrode, annealing processes(CFA,RTA) on the dielectric properties was discussed, the dielectric loss tangents of the film is 0.002—0.004, and the tunability of the dielectric constant is about 20%.3. The dielectric properties was tested under different frequencies, the result revealed that there was no obviously frequency-dependent, However, when the test frequency was 100 Hz,the C-V curve of BZN film capacitor deviated, which might be due to the polarization of space charge between thin film electrode and the defects.4. The dielectric property of BST and BZN was investigated, and the mechanism of both the tunable and the loss was discussed. Two kinds of materials were displacive type and order-disorder type respectively. Order-disorder type of BZN materials results in flattening of tunable curve and lower loss, while steeping of tunable curve and higher loss in displacive type BST.