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Research is presented concerning the investigation of the relationships which exist between the dielectric and microstructure properties of epitaxial films of ferroelectric barium titanate.

Research was conducted to examine the low frequency current noise in single electron transistors (SET) as a function of gain. it was found that the noise follows the gain in such a manner that the noise of the SET is dominated by input noise for almost all values of bias and gate voltage for the Al SET. However, it was found that there was a contribution from other sources when the gain is low for the Nb SET.

The transport properties of three terminal Josephson devices based on quasiparticle injection into YBa2Cu3O7-delta step-edge junctions have been studied. A surface layer with small electronic mean free path is used in examining the effects of surface roughness. Results indicate the presence of isotropic superconducting state in the layer. The surface density is gapless and shows an number of finite bias peaks while the midgap peak appears only at small roughness parameter.

A theoretical analysis and experimental evaluation of a hot-electron microbolometer with normal metal absorber for ultrasensitive detecting infrared and submillimeter wave were conducted. A normal metal hot-electron bolometer was fabricated with an absorber of very small volume, connected to an antenna by the Andreev NS-contacts. Results indicate that the parameters are considerably better than similar parameters of a voltage-biased superconducting transition edge bolometer.

Research was conducted to fabricate and test a high temperature superconducting Josephson mixer in submm-wave range. Mixer noise temperature of approximately 1100 K was established at 430 GHz. Its performance was enhanced with the use of junctions with low-inductance resistive shunt. A new method for the calculation of Josephson radiation linewidth from the IF noise dependence is proposed.

Research was conducted to investigate the dielectric properties of 400-600 nm thick epitaxial layers of SrTiO3 and Ba0.9Sr0.1TiO3 inserted between YBa2Cu3O7-delta or NdBa2Cu3O7-delta electrodes as functions of temperature and electric field. The highest tunability of the permittivity of a (600 nm) BSTO layer combined with high temperature superconducting electrodes was seen at temperatures around 300 K.

A single flux quantum (SFQ) voltage amplifier, RS-flip-flop and a toggle flip-flop were designed, fabricated and successfully tested. The three SFQ elements were designed using a single superconducting layer and optimized by several inductance calculations and computer simulations. Operation of up to 50 K was observed in the voltage amplifier, while operation at temperatures of uo to 30 K were demonstrated for both flip-flops.

High-quality YBa2Cu3O7 long Josephson junctions were developed using an improved approach based on an amorphous carbon mask technique and electron beam lithography. The junctions were fabricated across straight and sharp step edges on (001) LaAlO3 substrates. An applied magnetic field was used to linearly tune the flux-flow resonances observed in the current voltage curves of some long junctions.

A two-step process was used for the ex-situ growth of Tl-2212 thin films on different substrates. LaAlO3 and bicrystal substrates were also used for developing grain boundary weak links for direct current superconductive quantum interference devices (SQUIDs). The SQUIDs provide competitive noise levels, with low crossover frequency to 1/f noise and minimal flux and white noise levels.

A new design concept is proposed for fabricating rapid single flux quantum (RSFQ) logic circuits. The design approach uses a superconducting layer instead of a superconducting ground plane to increase the geometric size of the RSFQ cell and form narrow slit inductances with width comparable to the London penetration depth. It has been used in the fabrication of a high performance flip-flop cell.

A new technique is proposed for fabricating YBa2Cu3O7 step edge junctions on LaAlO3 substrates. The technique uses electron beam lithography to define the amorphous carbon films which are used in the junctions as ion milling masks. This approach significantly improves the straightness of the step edges and enhances the uniformity and sharpness of the step angles on the LaAlO3 substrates.