Effect of growth conditions on microstructure of BiFeO3-0.33BaTiO3 films and performance of bulk acoustic wave resonators

Abstract

The effect of growth conditions on the microstructure of BiFeO 3-0.33BaTiO 3 (BF-BT) films and the performance of bulk acoustic wave (BAW) resonators is analyzed using test structures with the BF-BT films grown at different positions relative to the plume axis in the pulsed laser deposition system. The BF-BT film grain size and surface roughness reveal a strong asymmetric surface distribution and decrease significantly in the film region facing the laser beam-plume interaction area. The (100) BF-BT texturing is enhanced in this film region. The variations in the BF-BT film microstructure result in corresponding variations of the BAW resonator performance. Their correlations are established using the model of the roughness induced attenuation of the reflected acoustic waves and theory of the dc field induced piezoelectric effect. The BAW resonators with the highest parameters are obtained in the BF-BT film region facing the laser beam-plume interaction area. The BAW resonators located in this film region reveal a mechanical Q-factor of 200 at 4.2 GHz, an effective electromechanical coupling coefficient of 10% and a tunability of the series resonance frequency of 4.5%. V

Ultrathin Ferroelectric Films: Growth, Characterization, Physics and Applications

“…It is worth to note that proper substrates such as SrTiO 3 and LaAlO 3 are more preferable for ferroelectric film based components than the standard Si wafers, due to their ability to provide good lattice matching to the perovskite ferroelectrics. More recently, Vorobiev et al [ 523 ] have studied the BAW performance in BiFeO 3 -0.33BaTiO 3 (BF-BT) films, demonstrating that the variations in the BF-BT film microstructure can result in corresponding variations of the BAW resonator performance, which allows for optimization of the deposition conditions and achieving the high resonator performance.…”