LAYERED STRUCTURES HTSC FERROELECTRIC, PREPARED BY SPUTTERING/

We have investigated some formation features of thin film structures P ZT/YBCO and YBCO/BSTO. PZT films have been synthesized by reactive ion beam sputtering of a multi-elemental metal target at room temperature and ''ex-situ'' annealing at 700-750 degrees C. BSTO and YBCO films h ave been deposited ''in-situ'' by magnetron sputtering of stoichiometr ic ceramic targets in an Ar + 50% O-2 gas mixture (pure oxygen for BST O) at temperature of 700 degrees C. Si(100) buffered with TiN to preve nt the diffusion in YBCO has been used as a substrate in the case PZT/ YBCO. The layers YBCO/BSTO have been deposited on MgO (100). The subst rates have been chosen according to prospective applications of PZT/YB CO as non-volatile memory cells integrated with existing CMOS transist or circuitry, and of YBCO/BSTO as voltage-tunable microwave devices. F ilms with composition Pb(Zr0.44Ti0.56)O-3 have been obtained by sputte ring of a target with a ratio of 13:36:51 for Pb, Sr and Ti, respectiv ely. The measured dielectric constant at 1 MHz in the structures Au/PZ T/YBCO/TiN/Si has been 540 acid the remnant polarization and coercive field values have been 5.4 mu C/cm(2) and 25 kV/cm, respectively. Plan ar capacitors with a dielectric of BSTO thin film and YBCO electrodes have been produced and investigated as voltage-controlled devices at 1 MHz. A controllability of epsilon(0 V)/epsilon(50 V) = 1.6 has been d emonstrated at 77 K. The dielectric hysteresis has been compared in ca pacitors with YBCO electrodes and with metal ones. It has been shown t hat the boundary phenomena at the interface of the epitaxially grown l ayers differ from that in the ferroelectric/metal structures and the h ysteresis effect diminishes significantly.