EFFECT OF SRTIO3 DEPOSITION TEMPERATURE ON THE DIELECTRIC-PROPERTIES OF SRTIO3 YBA2CU3O7-DELTA/LAALO3 STRUCTURES/

We report on the effect of the deposition temperature of SrTiO3 on the dielectric properties of SrTiO3/YBa2Cu3O7-delta/LaAlO3 thin film mult ilayer structures. In these structures, the YBa2Cu3O7-delta (YBCO) fil ms were deposited at 800 degrees C by laser ablation, followed by the in-situ deposition of the SrTiO3 (STO) layer at one of the following t emperatures: 750 degrees C, 650 degrees C, 550 degrees C, 450 degrees C, 350 degrees C, and 250 degrees C. Gold (Au) films were deposited an d patterned on top of the STO layer to form planar Au/STO/YBCO capacit or structures. The electrical response was studied by measuring the di electric constant (epsilon(r)) and loss tangent (tan delta) of the fer roelectric film from 300-40 K, at 1.0 MHz, and at electric fields up t o 100 kV/cm. Our results show 750 degrees C to be a deposition tempera ture which allows for large variations of epsilon(r) with applied fiel d, and with limited enhancement of tan delta. Lower deposition tempera tures cause a reduction of the induced change in epsilon(r) and an inc rease in tan delta with applied field.