In-field characterization of FeTe0.8S0.2epitaxial thin films with enhanced superconducting properties

ABSTRACTSuperconducting thin films of DyBa2Cu3O7-δ_ are deposited on MgO(100) substrates by an ozone-assisted coevaporation technique. At a relatively low substrate temperature (610°C) and with a fixed ozone flux we prepare highly c-axis oriented films with very good superconducting properties. The critical temperatures of the films are commonly above 85 K with critical currents above 10 5 A/cm2. We report on composition, microstructure, electrical resistivity and critical current of two good films.

Download Full-text

Epitaxial growth of “infinite layer” thin films and multilayers by rf magnetron sputtering

Journal of Materials Research ◽

10.1557/jmr.1998.0307 ◽

1998 ◽

Vol 13 (8) ◽

pp. 2195-2201 ◽

Cited By ~ 2

Author(s):

L. Fàbrega ◽

E. Koller ◽

J. M. Triscone ◽

Ø. Fischer

Keyword(s):

Thin Films ◽

Magnetron Sputtering ◽

Epitaxial Growth ◽

Alkaline Earth ◽

Rf Magnetron Sputtering ◽

Superconducting Properties ◽

Infinite Layer ◽

Semiconducting Behavior

We report on the preparation and characterization of epitaxial ACuO2 (A = Sr, Ca, Ba) thin films and multilayers with the so- called infinite layer (IL) structure, by rf magnetron sputtering. Films and multilayers without Ba have a remarkable crystal quality, whereas those containing this large ion are often multiphased and unstable. In spite of the excellent crystalline quality of these samples, obtaining thin films having both IL structure and displaying superconducting properties has not succeeded; our pure IL samples display semiconducting behavior, and the different procedures tried in order to dope them—annealings, introduction of disorder or cation vacancies, artificial layering—have failed. These results support that the pure IL structure ACuO2 (A = alkaline earth) cannot superconduct.

Download Full-text

Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106399 ◽

1988 ◽

Vol 46 ◽

pp. 866-867

Author(s):

E. L. Hall ◽

A. Mogro-Campero ◽

L. G. Turner ◽

N. Lewis

Keyword(s):

Thin Film ◽

Thin Film Deposition ◽

Superconducting Films ◽

Electron Beam Evaporation ◽

Film Deposition ◽

Silicon Substrates ◽

Superconducting Properties ◽

Sequential Electron ◽

Thin Superconducting Films

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.

Download Full-text

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154937 ◽

1989 ◽

Vol 47 ◽

pp. 592-593

Author(s):

J.B. Posthill ◽

R.P. Burns ◽

R.A. Rudder ◽

Y.H. Lee ◽

R.J. Markunas ◽

...

Keyword(s):

Thin Films ◽

Wide Band ◽

Deposition Process ◽

Heteroepitaxial Growth ◽

Electron Microscopic ◽

Wide Band Gap ◽

Lattice Matching ◽

Different Types ◽

Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Download Full-text

Processing and characterization of YBa2Cu3O7−x/Ag composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173364 ◽

1990 ◽

Vol 48 (4) ◽

pp. 46-47

Author(s):

Jafar Javadpour ◽

Bradley L. Thiel ◽

Sarikaya Mehmet ◽

Ilhan A. Aksay

Keyword(s):

Composite System ◽

Precursor Solution ◽

Microstructural Development ◽

Superconducting Properties ◽

Practical Applications ◽

Nitrate Precursor ◽

Cold Pressed ◽

Tape Cast ◽

Composite Samples

Practical applications of bulk YBa2Cu3O7−x materials have been limited because of their inadequate critical current density (jc) and poor mechanical properties. Several recent reports have indicated that the addition of Ag to the YBa2Cu3O7−x system is beneficial in improving both mechanical and superconducting properties. However, detailed studies concerning the effect of Ag on the microstructural development of the cermet system have been lacking. Here, we present some observations on the microstructural evolution in the YBa2Cu3O7−x/Ag composite system.The composite samples were prepared by mixing various amounts (2.5 - 50 wt%) AgNO3 in the YBa2Cu3O7−x nitrate precursor solution. These solutions were then spray dried and the resulting powders were either cold pressed or tape cast. The microstructures of the sintered samples were analyzed using SEM (Philips 515) and an analytical TEM (Philips 430T).The SEM micrographs of the compacts with 2.5 and 50 wt% Ag addition sintered at 915°C (below the melting point of Ag) for 1 h in air are displayed in Figs. 1 and 2, respectively.

Download Full-text