Effect of SrTiO3 Deposition Temperature on the Dielectric Properties of SrTiO3/YBa2Cu3O(7-delta)/LaAlO3 Structures

摘要

We report on the effect of the deposition temperature of SrTiO3 on the dielectric properties of SrTiO3/YBa2Cu3O(7-delta)/LaAlO3 thin film multilayer structures. In these structures, the YBa2Cu3O(7-delta) a (YBCO) films were deposited at 800 C by laser ablation, followed by the in-situ deposition of the SrTiO3 (STO) layer at one of the following temperatures: 750 C, 650 C, 550 C, 450 C, 350 C, and 250 C. Gold (Au) films were deposited and patterned on top of the STO layer to form planar Au/STO/YBCO capacitor structures. The electrical response was studied by measuring the dielectric constant (epsilon (sub r)) and loss tangent (tan delta) of the ferroelectric film from 300-40 K, at 1.0 MHz, and at electric fields up to 100 kV/cm. Our results show 750 C to be a deposition temperature which allows for large variations of epsilon(sub r) with limited enhancement of tan delta, while lower deposition temperatures cause a reduction of the induced change in epsilon(sub r) and an increase in tan delta with applied field.