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The design of the single-flux-quantum (SFQ) circuits which was estimated by applying over- and under-ground planes to minimize the parasitic inductances to determine its sheet inductances of base and counter superconducting layers is described.

A design of an up/down counter composed of 4-Junction Logic (JL) gates and the digital/analog (D/A) converter using an R-2R ladder circuit is presented to realize the digital flux locked-loop (FLL) circuit. The 4 JL gates with the Superconducting QUantum Interference Device (SQUID) regulator is developed and the correct logic operations are successfully confirmed using fabricated 4JL gates.

Photosensitive polyimide insulation layers are introduced to fabricate superconducting integrated circuits. It simplifies the fabrication process, because the photosensitive polyimide insulation layer can be patterned by conventional photolithography process, resulting in the etching process unnecessary in the present new fabrication process.

An innovative phonon detector in which the integrated coil and the normal-distribution junction are combined is described and discussed.

Nb1-xTixN thin films were prepared using reactive dc magnetron sputtering, and superconducting properties were found to be strongly linked to sputtering conditions.

Normal-distribution-shaped Josephson tunnel junctions for superconducting tunnel junction photon detector applications have been investigated.

CeO2 insulating film was utilized as a high temperature multilayer in the fabrication of a YBaCuO crossover. An adequate critical temperature of 87 L and critical current density of 1.0x10(super 5) A/cm2 were observed at the bottom YBaCuO bridges. Top bridges, however, exhibited a lower critical current density because the grain boundaries were developed at the bottom bridge's step edges.

X-ray irradiation was used to test a 200 micrometer x 200 micrometer surface area high-quality niobium-based superconducting tunnel junction. Application of a magnetic field with various ramping speeds revealed two types of stable operation modes. The single electron collection's higher mode operation energy requirement was 6.5 meV. Excellent response to x-rays of 5.9 keV and full width at half maximum of 93 eV were observed in the tunnel junction.

Experiments are performed to determine the feasibility of using superconducting tunnel junctions for high-energy resolution, x-ray detection. Characteristics of Nb-based junctions are studied to detect their responses to x-rays from synchrotron radiation. The dependence of the detector pulse height on x-ray energies falls somewhere between 4 and 15 keV.

A new etching process is proposed for fabricating submicron Nb/AlOx/Nb Josephson junctions for large-scale integration applications. The process uses a dummy etching process to improve the anisotropy in a reactive ion etching scheme. A scanning electron microscope is employed as an etching-end detector. The proposed etching scheme is very useful for producing high-quality submicron junctions with suitable critical current variations.

The effect of temperature on the critical current density profile of (103)-oriented YBaCuO/PrBaCuO/YBaCuO trilayer Josephson junctions is investigated by measuring their current-voltage characteristics at different temperatures. Results show that the junctions' critical current increases drastically at around 40 degrees Kelvin as temperature rises. This current decreases towards the critical temperature of the junctions.

A standard cell method that combines a routing process and automatic placement process yields a chip layout design for a high-speed Josephson LSI circuit comprising 1,500 gates that help analyze high-speed operability of a clock frequency of one GHz. A circuit dividing method that decreases the power supply circuit size and power wire length helps incorporate high frequency power into the chip layout design. A power load balancing technique achieves a steady power supply circuit operation.

The fabrication of all-oxide superconductor-normal metal-superconductor junction structures by the in-situ deposition of YBaCuO/PrBaCuO/YBaCuO trilayer films on a (100)MgO single crystal substrate is discussed. The junctions were patterned on the substrate using a conventional photolithographic technique. A gold layer was also deposited on the surface of the trilayer films to eliminate the influence of moisture and photoresist process. Experimental results show that the structures have a supercurrent with a small resistance connected in series to the junctions.

A proposed method for reducing logic delay uses a high Josephson critical current density with minimal junction area and is applied in the production of submicron NbN-MgO-NbN Josephson junctions. The resulting logic circuit is composed of junctions measuring 0.9 micrometers square. A minimum logic delay of 3.6 picosecond per gate is observed in the delay measurement resulting in a plus or minus 17% operating margin within 50 gates.

An Nb-based superconducting tunnel junction (STJs) is fabricated with Al trapping layer using the photosensitive polyimide insulation layer and was detected for X-ray irradiation. It was found that the method of using the photosensitive polyimide insulation layer practically applicable as X-ray detector.

A phonomediated radiation detector using Nb-based superconducting tunnel junctions is developed that are fabricated on an Al2O3 and LiNbO3 substrates. It is found that the maximum pulse height of the phonon events for the LiNbO3 substrate is about twice of that for the Al2O3 substrate.elp

Fabrication of Nb-based suerconducting tunnel junctions (STJ) with [beta]-Ta trapping layers is described and discussed.