Barrier properties in YBa 2 Cu 3 O 7؊x grain-boundary Josephson junctions using electron-beam irradiation

Electron-beam irradiation has been used to induce controllable variations in the properties of YBa 2 Cu 3 O 7Ϫx biepitaxial grain-boundary Josephson junctions. A correlation between the transport properties and the microstructure was obtained by determining the ratio of a barrier thickness to the dielectric constant of the junctions with different barriers. These results give evidence of the role of the oxygen content and the dielectric constant of the interface region in transport phenomena. The experiment also demonstrates frequency tunability in a resonant soliton oscillator. ͓S0163-1829͑98͒51322-2

A study of barrier properties in YBaCuO grain boundary Josephson junctions using electron beam irradiation

Electron-beam irradiation has been used to induce controllable variations in the properties of YBa2CU3O7-x biepitaxial grain-boundary Josephson junctions. A correlation between the transport properties and the microstructure was obtained by determining the ratio of a barrier thickness to the dielectric constant of the junctions with different barriers. These results give evidence of the role of the oxygen content and the dielectric constant of the interface region in transport phenomena. The experiment also demonstrates frequency tunability in a resonant soliton oscillator

Electron beam irradiation YBaCuO grain boundary Josephson junctions

The properties of the Y1Ba2Cu3O72x biepitaxial Josephson junctions were reproducibly modified by a focused electron beam irradiation of the interface region. The junctions were fabricated by depositing Y1Ba2Cu3O72x thin film by cylindrical magnetron sputtering technique on the ~110! SrTiO3 substrate, partially covered by a pregrown MgO seed layer. The junction parameters can be adjusted controllably by applying an appropriate dose. Electron irradiation decreased the critical current of the junctions IC and increased the normal state resistance times area to values of the order of 1(m V cm2). Some other effects, such as the disappearance of the excess current, were also observed. The original properties of the junctions could be partly restored by isothermal annealing. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the properties of irradiated junctions

Electron beam writing in fabricating planar high Tc Josephson junctions

Electron beam irradiation was utilized to fabricate planar Josephson junctions in Y1Ba2Cu3O7 thin films. After the micron-size bridges had been fabricated by way of standard optical lithography, they were modified using a well focused nanometer STEM probe with beam energy within the range of 80 - 120 keV. Modified junctions exhibit a two-step normal/superconductor transition. We attribute the lower transition temperature, which is of the order of 77 K, to the transition of the damaged region. Shapiro steps under applied microwave radiation of the frequency 10-15 GHz, as well as oscillation of the critical current in a magnetic field were observed up to 70 K. A comparison with the RSJ model is made and a possible damage mechanism is discussed

Modification of the properties of YBaCuO biepitaxial Josephson junctions through electron beam irradiation

The properties of YBa2Cu3O7-x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the biepitaxial technique on (110) SrTiO3, substrates. The technique utilizes the property of YBa2Cu3O7-x film to grow (103)-oriented on the bare substrate and (001)-oriented on the part of the substrate with the MgO seed layer, providing Josephson junctions of good quality and excellent reproducibility. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions I-C and increased the normal state specific resistivity. The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the transport properties of irradiated junctions

Effects induced by electron beam irradiation on YBaCuO Josephson structures: a new approach to control the junction properties

The properties of YBa2Cu3O7-x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the property of YBa2Cu3O7-x film to grow (103)-oriented on the bare (110) SrTiO3 substrate and (001)-oriented on the part of the substrate with the MgO seed layer. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions Ic and increased the normal state specific resistivity. The shift of the voltage position of the Fiske steps was also observed. Isothermal annealing partly restores the original junction properties. A correlation between the transport properties and the microstructure was obtained by determining the ratio of a barrier thickness to the dielectric constant of the junctions with different barriers. These results give evidence of the role of the oxygen content and the dielectric constant of the interface region in transport phenomena. The experiment also demonstrates frequency tunability in a resonant soliton oscillator

Modification of the properties of Y1 Ba2Cu3O7-x biepitaxial Josephson junctions by electron beam irradiation

The properties of YBa2Cu3O7-x grain boundary Josephson junctions have been reproducibly modified by a focused electron beam irradiation. The original junctions were fabricated by using the biepitaxial technique on (110) SrTiO3, substrates. The technique utilizes the property of YBa2Cu3O7-x film to grow (103)-oriented on the bare substrate and (001)-oriented on the part of the substrate with the MgO seed layer, providing Josephson junctions of good quality and excellent reproducibility. The junction parameters can be adjusted controllably by applying an appropriate irradiation dose. Electron irradiation reduced the critical current of the junctions I-C and increased the normal state specific resistivity. The disappearance of the excess current and the shift of the voltage position of the Fiske steps were also observed. Isothermal annealing partly restores the original junction properties. We also speculate that some aspects of the nature of the grain boundary barriers can be better understood from the study of the transport properties of irradiated junctions