Epitaxial thin films of YBa2C!u307 have been prepared on SrTiOs and LaAlOs substrates by a high-pressure planar dc-sputtering technique. By covering the substrate heater with a frame of polycrystalline YBazCu30~ -substantial improvements of the YBa2Cu307 film properties were achieved. These are characterized by dc-resistivity values p(T) of less than 50 @I cm at 100 K and ~(300 K)/p( 100 K) values of up to 3.9. Significant deviations from the usual linear p(T) behavior were found. Critical temperatures above 90 K, resistive transition widths down to 0.3 K, and critical current densities of about 5 x lo6 A/cm2 at 77 K confirm the high quality of the films. As indicated by Rutherford backscattering and high-resolution transmission electron microscopy the films exhibit a microstructure characterized by a reduced density of lattice defects. However, lattice-coherent precipitates with a diameter of about 5-10 nm were observed. As an outstanding feature the films exhibit, besides the initial steep falloff at T, a further gradual decrease of the microwave surface resistance at 87 GHz below 50 K by at least one order of magnitude. These results are very promising for millimeter-wave applications of epitaxial YBaz.Cu307 thin films.

Our results demonstrated that IL-9 exerted pro-atherosclerotic effects in ApoE-/- mice at least partially by inducing VCAM-1 expression, which mediated inflammatory cell infiltration into atherosclerotic lesions.

The performance of nitride-based LEDs was improved by inserting dual stage and step stage InGaN/GaN strain relief layer (SRL) between the active layer and n-GaN template. The influences of step stage InGaN/GaN SRL on the structure, electrical and optical characteristics of GaN-based LEDs were investigated. The analysis of strain effect on recombination rate based k·p method indicated 12.5% reduction of strain in InGaN/GaN MQWs by inserting SRL with step stage InGaN/GaN structures. The surface morphology was improved and a smaller blue shift in the electroluminescence (EL) spectral with increasing injection current was observed for LEDs with step stage SRL compared with conventional LEDs. The output power of LEDs operating at 20 mA was about 15.3 mW, increased by more than 108% by using step stage InGaN/GaN SRL, which shows great potential of such InGaN/GaN SRL in modulating InGaN/GaN MQWs optical properties based on its strain relief function.

We have produced submicrometre wide bicrystal Josephson junctions on the basis of YBa 2 Cu 3 O 7−δ (YBCO) films and investigated their microstructure and superconducting properties. A 300 nm thick buffer layer of SrTiO 3 on the SrTiO 3 bicrystal substrates has helped to improve the quality and reproducibility of the junctions. The surface of the films at the grain boundary (GB) was investigated by high-resolution scanning electron microscopy (HRSEM). This has revealed one unit cell steps on the YBCO film surface and meandering of the GB in the YBCO film. Planar transmission electron microscopy investigations of the junction have confirmed that the GB in YBCO had a linear deviation from the underlying GB in the substrate up to ∼0.4 µm. The observed spread of the angles of the deviation of the GB in the film from the direction of the GB in the substrate on the slot-and other defect-free parts of the GB was below 10 • . Due to the d-wave symmetry of the order parameter in YBCO the reduction of the curvature of the GB leads to an improvement of the homogeneity of the current flow and a doubling of the critical current I c of the junction. The observed I c R n product of symmetric 20 • bicrystal junctions was ∼400 µV at 77.4 K and ∼1 mV at 63 K. Integration of such junctions in SQUIDs with a square 16 mm multilayer flux transformer has allowed us, for the first time, to reach a field resolution for the high-T c magnetometers of ∼3.5 fT Hz −1/2 at 77.4 K.

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In this study we successfully bonded silicon wafer substrates with metal based thermocompression technology. This technology has the advantage of inherent possibility of hermetic sealing and electrical contact. We used three different kinds of metals: gold, copper and aluminum. We will show the hermeticity, bonding strength and reliability of the different processes and compare the results

A multilayer thin film epitaxial passivation of single crystal MgO substrates was developed. YBa2Cu3O7−x films on the buffered MgO substrates demonstrate pure c-axis orientation, absence of in-plane disoriented grains, transition temperature Tc>91K, and critical current density Jc∼5MA∕cm2 at 77.4K and were deposited in thicknesses of up to several micrometers without cracks. High-temperature superconductor multilayer flux transformers of 2μm thickness on the buffered MgO substrates demonstrated improved insulation between the superconducting layers and an increased dynamic range compared to flux transformers on SrTiO3 substrates.

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