International Business Machines Corporation

Darrell G Schlom

Jochen D Mannhart

Carl A Mueller

Johannes Georg Bednorz

Frank Lichtenberg

Johannes G Bednorz

Frank Litchenberg

This method for manufacturing lattice-matched substrates for high-T.sub.c superconductors employs at least two materials chosen from the group of known suitable substrate materials, of which one has a lattice constant smaller than the lattice constant(s) of the perovskite subcell of the selected superconductor material, while the other one has a lattice constant greater than the lattice constant of the perovskite subcell of the selected superconductor. These materials are then powdered and mixed intimately for providing a single-crystal either from the molten mixture of the chosen materials or by thin film deposition, said single-crystal containing appropriate molar percentages of the chosen materials so that resulting lattice constant is essentially the same as that of the selected superconductor material.

Method for manufacturing lattice-matched substrates for high-T.sub.c

Proposed is a method for operating a field-effect device comprised of a superconducting current channel having source and drain electrodes connected thereto, said superconducting current channel being separated from a gate electrode by an insulating layer, where the resistance of said current channel is controlled by varying the critical current of the superconducting material through the application of an electrical field across the superconducting current channel, which in turn changes the density of the mobile charge carriers in the superconducting material. Taught is also an inverted MISFET device for performing that method, the device being characterized in that on an electrically conductive substrate an insulating layer is provided which in turn carries a layer consisting of a superconducting material, and that a gate electrode is attached to said substrate, and source and drain electrodes are electrically connected to said superconductor layer. Advantageously, between the substrate and the superconducting layer, a metallic passivation layer may be provided.

Superconductive-channel electric field-effect drive

A method for manufacturing a high Tc superconducting circuit elements is disclosed, which comprises the steps of preparing a single crystal conductive substrate of Sr.sub.2 RuO.sub.4 by a floating zone melting process; epitaxially growing on the (001)-surface of the Sr.sub.2 RuO.sub.4 substrate a high Tc copper oxide-based superconducting film with a thickness of 1 to 1000 nm; depositing metal pads onto said superconducting film to form electrical contacts; and applying a metal pad to the surface of the substrate to form an electrical contact.

Method for manufacturing high T.sub.c superconducting circuit elements

These superconducting circuit elements, namely SNS heterostructures, such as, e.g. Josephson junctions and field-effect transistors, have a sandwich structure consisting of at least one layer of high-T.sub.c superconductor material arranged adjacent to a metallic substrate, possibly with an insulating layer in between, the substrate, the superconductor and--if present--the insulator all consisting of materials having at least approximately matching molecular structures and lattice constants. Electrical contacts, such as source, drain and gate electrodes are attached to the superconductor layer and to the substrate, respectively. The electrically conductive substrate consists of a metallic oxide such as strontium ruthenate Sr.sub.2 RuO.sub.4, whereas the superconductor layer is of the copper oxide type and may be YBa.sub.2 Cu.sub.3 O.sub.7-.delta., for example. The insulator layer (10) may consist of SrTiO.sub.3. The manufacture of these devices starts with the preparation of the substrate material from a 2:1,1 molar ratio of SrCO.sub.3 to RuO.sub.2 and involves a floating zone melting process yielding single crystals of the strontium ruthenate Sr.sub.2 RuO.sub.4 material onto whose (001) surface the superconductor layer as well as the barrier layer can be epitaxially deposited.

Superconducting circuit elements with metallic substrate and method for

An inverted MISFET structure with a high transition temperature superconducting channel comprises a gate substrate, an interfacial layer with one or more elements of the VIII or IB subgroup of the periodic table of elements, an insulating layer and a high transition temperature superconducting channel. An electric field, generated by a voltage applied to its gate alters the conductivity of the channel.

Growing community of inventors

State College, PA, United States of America

Darrell G Schlom