Changes in the structural and electrophysical properties of Ba0.8Sr0.2TiO3 films with decreasing thickness

Comparative studies of structural and electrophysical properties were performed for Ba0.8Sr0.2TiO3 (BSTO) films with the thickness of 100 nm, 120 nm and 350 nm. The surface morphology, the domain structure and local polarization switches were explored in the ferroelectric phase whereas high-frequency capacitance-voltage characteristics were measured in the paraelectric phase at 121 degrees C. It was shown that good crystalline properties of the BSTO surface and grains are preserved until the thickness of ceramic layers decrease to 100 nm. The surface roughness did not exceed 2 - 4 nm and the average radius grains was in the range of 64 - 87 nm. Polarization domains induced with a microscope tip were stable and are conserved for several hours. Electrophysical properties of Ba0.8Sr0.2TiO3 films in the paraelectric phase strongly depend on the thickness of layers of BSTO ceramics. Effective dielectric permittivity of BSTO in the limit of weak fields decreases when the film thickness decreases from 350 nm to 100 nm from 920 to 400. (C) 2020 Elsevier Ltd. All rights reserved.