Chemical processing and properties of Sr₂(Ta, Nb)₂O₇ thin films

Abstract

The crystallographic orientation, microstructure and electrical properties of Sr₂(Ta, Nb)₂O₇ thin films strongly depended on the composition (Ta:Nb). Post-annealing at 850°C was effective for the improvement of some properties. The thin films with relatively Nb-rich compositions, such as Sr₂(Ta_0.6Nb_0.4)₂O₇ and Sr₂(Ta_0.5Nb_0.5)₂O₇, showed the (0k0) preferred orientation. The Sr₂(Ta_0.5Nb_0.5)₂O₇ thin film had a lamination layer structure after the post-annealing at 850°C for 6 min in oxygen. The characteristic microstructure originated in the crystallographic orientation of (0k0), which is the cleavage plane, and influenced electrical properties. The dielectric constant little change with the composition, however, the P-E hysteresis properties improved with the Nb content.

Key Words:

• Sr₂(Ta; Nb)₂O₇ ferroelectric thin films
• chemical processing
• composition dependence
• crystallographic orientation
• microstructure development
• electrical properties