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We study the propagation of terahertz bandwidth electrical pulses on high critical current density c-axis oriented YBa2Cu3O7-δ (YBCO) coplanar transmission lines deposited epitaxially on the low dielectric loss substrate lanthanum aluminate (LaAlO3). The losses on the YBCO transmission line are lower than on an equivalent gold line on the same substrate at temperatures below 50 K. At higher temperatures, absorption and dispersion of the ultrashort electrical pulses are observed in reasonable agreement with Mattis–Bardeen theory. [ABSTRACT FROM AUTHOR]

We report on a new process to make films of Y1Ba2Cu3O7 using coevaporation of Y, Cu, and BaF2 on SrTiO3 substrates. The films have high transition temperatures (up to 91 K for a full resistive transition), high critical current densities (106 A/cm2 at 81 K), and a reduced sensitivity to fabrication and environmental conditions. Because of the lower reactivity of the films, we have been able to pattern them in both the pre-annealed and post-annealed states using conventional positive photoresist technology. [ABSTRACT FROM AUTHOR]

We have fabricated 30-nm lines on 200-nm centers in CaF2 using a scanning transmission electron microscope. The lines were written by electron beam radiolysis of a fine grain polycrystalline CaF2 film and reaction to CaO followed by development in H2O. [ABSTRACT FROM AUTHOR]

Reports on the fabrication of YBa[sub2]Cu[sub3]O[sub7-δ]-normal metal-YBa[sub2]Cu[sub3]O[sub7-δ]step-edge Josephson junctions that fit the resistively shunted junction model with Johnson-Nyquist thermal noise. Expression for the ratio of the thermal energy to the supercurrent energy; Solution to the Smoluchowski equation.

The range and intensity of backscattered exposure from a silicon substrate were measured as a function of incident electron energy. The range is proportional to the energy to the 1.7 power. The integrated energy deposited at the silicon surface by backscattered electrons is about 0.8 of the energy deposited by the incident electrons and is nearly independent of the incident beam electron energy. These results show that the severity of the proximity effect, the exposure of regions not addressed by the beam, can be reduced by using high beam energy since the backscattered electrons are spread over a distance much larger than minimum feature sizes. [ABSTRACT FROM AUTHOR]

A fundamental parameter of sample quality in epitaxial films of high Tc oxides is the effective penetration depth λ|| of the superconducting sheet. A contactless audio-frequency method is described, in which an epitaxial YBa2Cu3O7 film is sandwiched between sets of stacked coils, and the procedure is given for computing the complex sheet impedance and hence λ|| from the change in mutual inductance produced by screening currents in the film. Temperature dependence of the complex impedance is presented. [ABSTRACT FROM AUTHOR]

Presents a study which measured the complex conductivity of thin superconducting niobium films using coherent time-domain terahertz spectroscopy. Experimental procedure; Results of the study; Conclusion.

Deals with a study which measured the basic interconnection performance of superconducting thin-film microstrip interconnection, with a sapphire dielectric and a superconducting ground plane. Transition temperature of superconducting microstrip transmission lines; Methodology of the study; Results and discussion.

Presents a study which examined the developed novel technique for measuring the dielectric constant and loss tangent of a thin film dielectric material. Experimental technique; Experimental results; Conclusions.

In an effort to develop HTS superconducting filters with sufficient power handling capability for PCS (Personal Communication Services) base station transmit applications, we have undertaken a study of the power dependence of large area YBCO thin films on LaAlO/sub 3/ substrates. We employed a coplanar-wave-guide (CPW) resonator technique to obtain the changes of loss and inductance versus circulating microwave currents in the films. Data have been collected on uniform large area (2" diameter) films grown by coevaporation and off-axis sputtering techniques under varying deposition conditions. We found correlations between the RF power dependence and other film properties such as penetration depth and crystal structure. The most intrinsic sample, from the coevaporation technique, characterized by the smallest penetration depth, good orthorhombicity and absence of tetragonal phase, shows the least amount of nonlinearity. Such correlations can be used to prescreen films for fabrication and monitor the film production line. However, films from coevaporation and off-axis sputtering show very distinct power dependent behaviors. [ABSTRACT FROM PUBLISHER]

Presents an electromagnetic model for planar stripe inductors based on thin metallic magnetic films. Application of magnetic films in high frequency planar magnetic flux devices; Structure of the electromagnetic model.

Structures as small as 20 nm have been fabricated in GaAs by high-resolution electron beam lithography and reactive ion etching. NiCr patterns were formed on the semiconductor surface by liftoff of a single-layer electron beam resist. This metal mask pattern was transferred into the III-V material by etching in a SiCl4 plasma [ABSTRACT FROM AUTHOR]

We have studied the effect of ion beam irradiation on the microstructure of epitaxial YBa2Cu3O7-δ thin films. The ion beam induced defects are found to cluster in small (<100 Å) disordered areas. The size and density of the disordered areas are found to increase with the ion fluence. The presence of these small disordered areas can lead to the reduction of phase coherence of the electron pair wave function. Ion beam irradiation is also found to reduce the orthorhombicity of the lattice structure. A new incommensurate superlattice phase due to ion beam induced defect ordering has also been observed. [ABSTRACT FROM AUTHOR]

We have studied the effect of visible and near-infrared light on the electrical properties of superconducting thin films of YBa2Cu3O7-δ. The responses we observe can all be explained in terms of light heating the film to a temperature above the superconducting transition. No evidence that the light directly affects superconductivity was found. [ABSTRACT FROM AUTHOR]

We have demonstrated the existence of circumferential persistent currents in Ba2YCu3O7 ceramic toroids at 77 and 4.2 K and in thin films at 77 K. The field dependence of the critical current densities obtained from these persistent current measurements at 77 K is in fair agreement with that obtained from transport measurements. The persistent critical current densities for fields less than 10 G are 150 A/cm2 for the ceramic at 77 K and 105 A/cm2 for the thin film. A long term experiment showed that the resistivity is less than 3×10-18 Ω cm at 77 K. [ABSTRACT FROM AUTHOR]

We have investigated power handling of high-temperature superconducting microstrip filters employing highly sensitive thermal imaging. At low power, the images show small heating effects localized to areas with high current densities (ΔT<0.5 K), consistent with the known surface resistance and simulations of the current distribution. The breakdown at high-power levels, however, is always nucleated by a frequency independent local hot spot (T>=Tc). Scanning electron microscopy analysis of this area reveals a flaw in the superconducting material, presumably reducing the local critical current. The maximum power handling of these filters is, therefore, still open to improvement. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]