Dajun Wu

Dielectric enhancement of Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 multilayered thin films fabricated by chemical solution deposition

Multilayered Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 thin films with different deposition sequences were deposited on Pt/Ti/SiO2/Si substrates by chemical solution deposition method. Obvious dielectric enhancement occurred in Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 multilayered thin films due to Maxwell-Wagner affect, but not happened in Ba0.5Sr0.5TiO3/Ba0.7Sr0.3TiO3 multilayered thin films because of the different interface quality caused by different deposition sequences. The dielectric constant and tunability of Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 multilayered thin films at 200 kHz (590 and 46%, respectively) were higher than that of Ba0.7Sr0.3TiO3 and Ba0.5Sr0.5TiO3 monolayer thin films (470, 32% and 430, 29%, respectively). Besides, the dielectric loss tangent of Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 multilayered thin films (0.025) was lower than that of Ba0.7Sr0.3TiO3 and Ba0.5Sr0.5TiO3 monolayer thin films (0.033, 0.052, respectively). Comparing with that of Ba0.7Sr0.3TiO3 and Ba0.5Sr0.5TiO3 monolayer thin films, the dielectric properties of Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 multilayered thin films had certain of improvement, which is of benefit to applications in tunable microwave devices.

Dielectric Enhancement Effect in (Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3)n (n = 1,2,3,4) Multilayered Thin Films Deposited by Chemical Solution Deposition Method

Multilayered Ba0.7Sr0.3TiO3/Ba0.5Sr0.5TiO3 (BST0.7/0.5)n (n = 1, 2, 3 and 4, respectively) thin films with different layered periods are prepared on Pt/TiO2/SiO2/Si substrates by chemical solution deposition method. The microstructure and dielectric properties of the films are investigated systematically. Obvious dielectric enhancement occurs in (BST0.7/0.5)n multilayer comparing with Ba0.5Sr0.5TiO3 and Ba0.7Sr0.3TiO3 monolayered thin films due to Maxwell-Wagner effect. On the other hand, strain and grain sizes of the multilayered thin films can also affect the dielectric properties. Specially, the (BST0.7/0.5)2 shows the best dielectric properties with dielectric constant of 557, loss tangent of 0.025 and tunability of 46% at 200 KHz, which is beneficial in applications.