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A study is conducted on a 160-nm-thick (Hg0.9Re0.1)Ba2CaCu2Oy [(Hg,Re0-1212] epitaxial thin films that were fabricated on 2degree-18.4degree -tilt SrTiO3 vicinal substrates with thin buffer layers. The studies indicate that the vicinal films had superior crystallinity and superconducting properties comparable to those for conventional films with no tilt.

The packaging and assembling techniques for the bit error rate (BER) measurement system is examined and the system configuration is improved to obtain a lower measurable limit of BER. This led to a BER less than 10(sup -12) at an output voltage of 1.7 and 2.3 mV for ducting microstrip-line to coplanar-waveguide transmission-line converter.

Interface-engineered ramp-edge Josephson junctions with different critical current values and different electrode materials are investigated by transmission electron microscopy. La doping seems to suppress the formation of Y(sub 2)O(sub 3) and reduce the lattice mismatch between the barrier and the electrodes.

High temperature superconducting rapid single flux quantum circuits were fabricated and tested using interface engineering Josephson junction.

Research is presented describing the study of surface barriers of Josephson junctions which have modified ramp-edges resulting in differing superconductivity levels.

Inductive coupling between Quantum-Flux-Parametron (QPF) gates for signal transfer is proposed in place of the direct coupling method as a means of improving the signal isolation. Inductively coupled gates were used to design and fabricate majority gates, which are the principal logic elements of the QFP circuits. Transient properties of the QFP gates upon application of an activation current were also examined by the numerical simulation.

A proposed measurement method for the critical current (I (sub c)) distribution for the resistively shunted junctions (RSJs) is described. The I(sub c) distribution of the RSJ-type junction is examined by arraying the junctions in series. The factors responsible for the I(sub c) spread, the integration scale and the conditions under which the I(sub c) measurement method can be used are discussed. The proposed method is applicable to any other RSJ-type junctions.

The properties of (Hg,Re)[Ba.sub.2]Ca[Cu.sub.2][O.sub.y] ((Hg,Re)-1212) [100]-tilt junctions are described for this two types of [100]-tilt junctions, that is, a mountain-type junction and a valley-type junction of which a-b planes formed a mountain shape and a valley shape along the grain boundaries, respectively are compared. The hysteresis behavior is explained by flux penetration between the Cu[O.sub.2] planes that is associated with the large anisotropy of (Hg,Re)-1212.