Fabrication and characterization of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///SrTiO/sub 3//Ag trilayer films on SrTiO/sub 3/ bicrystal substrates

We have fabricated YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta///SrTiO/sub 3//Ag trilayer thin films on bicrystal SrTiO/sub 3/ substrates for electric field effect three terminal devices. For the electrical transport measurements the samples were patterned using optical lithography and wet or ion beam etching. The dielectric properties of the SrTiO/sub 3/ barrier layer were analyzed by measuring the temperature and voltage dependence of the relative dielectric constant /spl epsiv//sub r/ and the resistivity /spl rho//sub iso/. By optimization of the deposition process, /spl rho//sub iso/=2/spl times/10/sup 10/ /spl Omega/m and a breakdown voltage E/sub bd/=1/spl times/10/sup 7/ V/m were obtained at 4.2 K. For /spl epsiv//sub r/ a maximum value of 460 was observed around 75 K. By the deposition of the trilayer structure on bicrystal substrates, gated grain boundary Josephson junctions (GBJs) were fabricated. High quality GBJs have been obtained covered by a SrTiO/sub 3/ gate insulator with a maximum change in the polarization of 0.08 C/m/sup 2/.