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The Josephson properties of high temperature superconducting (HTS) junctions fabricated via focused electron beam writing are investigated under steady-state conditions. The junctions' current-voltage characteristics are measured together with the transition to flux flow and magnetic field modulation. Results show that the HTS junctions exhibit near-ideal RSJ characteristics and uniform current distribution in a very narrow temperature interval.

A coherent time-domain spectroscopy method is employed to measure the transmission and phase shift of 0.2-1.5 THz radiation on unpatterned, high grade YBa2Cu3O7 superconducting films. The measurements are carried out at selected temperatures in the normal and superconducting states. Results show that the electromagnetic penetration depth for the films has a modest frequency dependence below the critical temperature. This indicates that the carrier scattering rate collapses rapidly below the critical temperature.

A comparative study of magnetic field sensitivities of variable thickness bridge (VTB) arrays manufactured in YBCO, BSCCO and TBCCO thin films reveals that VTB arrays made with YBCO are not suitable for functioning as superconducting flux flow transistors. The study involves the measurement of volt-ampere characteristics of the arrays in low uniform and nonuniform magnetic fields. The VTB arrays do not have any measurable effect on control line magnetic fields. Thermal processes are capable of inducing large values of current gain and transresistance.

Examination of the low frequency noise in Y-Ba-Cu-O thin films near the transition temperature region reveals that the voltage noise power spectra is directly proportional to the square of the dc bias current and the square of the temperature coefficient of the resistance, but is inversely related to the volume of the device. Experimental data suggest that equilibrium local temperature fluctuation is the origin of low frequency noise in Y-Ba-Cu-O thin films near the transition region. Voltage noise power spectral density lower cutoff frequency predicted by the temperature fluctuation model agrees with that of experimental data.

Statistical information for junction processes are estimated by the use of linewidths of phase-locked, oscillating arrays of high temperature superconducting Josephson junctions. Fitting processes are applied in the simulation of results. Arrays with numerous phase-locked junction operations help characterize and develop junction processes. Normal state resistances spread the critical current for three different processes of step-edge electron-beam and SNS nanobridge formation.

The dielectric features of a new insulating perovskite Sr2AlTaO6 (SAT) films and the changes in the structure and electrical properties of the high temperature superconductor YBa2Cu3O7 on LaAlO3 substrates due to SAT were examined. This involved the utilization of x-ray rocking curve and Rutherford backscattering channelling measurements on the SAT films. The applicability of SAT to bilayer and trilayer superconducting devices was demonstrated.

A proposed flux flow logic family is developed to address problems in interfacing with conventional circuitry and efficiency in superconducting memory cells. Although not as fast as the Josephson logic family, the proposed superconducting flux flow transistor can easily be implemented at 77 K and has very low power levels with a fast, small and natural flip-flop. Results show that the impedance and signal levels can act as interface between the Josephson logic and conventional circuitry.