Method of making artificial layered high T.sub.c superconductors

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring the operating temperature of the current substrate surface, monitoring, prior to said exposure the operating temperature of the source of the particular constituent material and from the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• p1 repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• and
• said gas phase contains the metal atoms to be deposited in the form of an organic compound of the particular metal.

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring, prior to said exposure the operating temperature of the current substrate surface, monitoring prior to said exposure the operating temperature of the source of the particular constituent material and monitoring prior to said exposure the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• and
• said monocrystalline substrate contains of octahedral strontium titanate SrTio.sub.3, that in a first epitaxial operation a first monomolecular layer of lanthanum oxide La.sub.2 O.sub.3 is deposited onto said strontium titanate substrate, that in a second epitaxial operation a layer of octahedral cuprous oxide Cu.sub.2 O is deposited onto said lanthanum oxide monolayer, that in a third epitaxial operation a second monolayer of lanthanum oxide La.sub.2 O.sub.3 is deposited onto said cuprous oxide layer, that in a fourth epitaxial operation a monolayer of octahedral titanium dioxide TiO.sub.2 is deposited onto said second lanthanam oxide monolayer, the four individual epitaxial operations being performed under controlled conditions regarding time of exposure, concentration of epitaxial source material, and reaction temperature so as to permit the nascent la.sub.2 CuTiO.sub.6 crystal to be stoichiometrically correct and to assume a layered, ocathedral structure of the ABB' type.

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring prior to said exposure the operating temperature of the current substrate surface, monitoring prior to said exposure the operating temperature of the source of the particular constituent material and monitoring prior to said exposure the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• and
• said monocrystalline substrate consists of octahedral strontium titanate SrTiO.sub.3, that in a first epitaxial operation a monomolecular layer of lanthanum oxide La.sub.2 O.sub.3 is deposited onto said substrate, that in a second epitaxial operation a monolayer of mixed aluminum oxide Al.sub.2 O 3+/3 and zirconium oxide Zr.sup.4+ O.sub.2 is deposited onto said layer of lanthanum oxide, that in a third epitaxial operation a second layer of lanthanum oxide La.sub.2 O.sub.3 is deposited onto said monolayer of mixed oxides, and that in a fourth epitaxial operation octahedral cuprous oxide Cu.sub.2 O is deposited onto said second monolayer of lanthanum oxide, the four individual epitaxial operations being performed under controlled conditions regarding time of exposure, concentration of epitaxial source material, and reaction temperature so as to permit the nascent La.sub.2 Cu(Al.sub.1/2,Zr.sub.1/2)O.sub.6 crystal to be stoichiometrically correct and to assume a layered, octahedral structure of the ABB' type.

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring prior to said exposure the operating temperature of the current substrate surface, monitoring prior to said exposure the operating temperature of the source of the particular constituent material and monitoring prior to said exposure the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• and
• said monocrystalline substrate consists of octahedral strontium titanate SrTio.sub.3, that in a first epitaxial operation a first monomolecular layer of lanthanum oxide La.sub.2 O.sub.3 is deposited onto said monocrystalline substrate, that in a second epitaxial operation a first monomolecular layer of octahedral cuprous oxide Cu.sub.2 O is deposited on to said lanthanum oxide layer, that in a third epitaxial operation a first monomolecular layer of strontium oxide SrO is deposited onto said monolayer of cuprous oxide, that in a fourth epitaxial operation a first monomolecular layer of tungstic oxide WO.sub.3 is deposited onto said first strontium oxide monolayer, that in a fifth epitaxial operation a second monomolecular layer of strontium oxide SrO is deposited onto said monomolecular layer of tungstic oxide, that in a sixth epitaxial operation a second monomolecular layer of octahedral cuprous oxide Cu.sub.2 O is deposited onto said second strontium oxide layer, and that in a seventh epitaxial operation a second monomolecular layer of lanthanum oxide LaO is deposited onto said cuprous oxide layer, the seven individual epitaxial operations being performed under controlled conditions regarding time of exposure, concentration of epitaxial source material, and reaction temperatures so as to permit the nascent Sr.sub.2 LaCu.sub.2 WO.sub.9 crystal structure of the AA'B type.

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring prior to said exposure the operating temperature of the current substrate surface, monitoring prior to said exposure the operating temperature of the source of the particular constituent material and monitoring prior to said exposure the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• and
• said monocrystalline substrate consists of octahedral strontium titanate SrTiO.sub.3, that in a first epitaxial operation a first monomolecular layer of yttrium oxide Y.sub.2 O.sub.3 is deposited onto said monocrystalline substrate, that in a second epitaxial operation a first monomolecular layer of pyramidic cuprous oxide Cu.sub.2 O is deposited onto said yttrium oxide layer, that in a third epitaxial operation a first monomolecular layer of barium oxide BaO is deposited onto said monolayer of cuprous oxide Cu.sub.2 O, that in a fourth epitaxial operation a layer of ribbon of square planar copper oxide CuO.sub.4 polyhedra is deposited onto said barium oxide layer, that in a fifth epitaxial operation a second monomolecular layer of barium oxide BaO is deposited onto said layer of copper oxide polyhedra, that in a sixth epitaxial operation a second monomolecular layer of pyramidic cuprous oxide Cu.sub.2 O is deposited onto said second barium oxide layer, and that in a seventh epitaxial operation a second monomolecular layer of yttrium oxide is deposited onto said cuprous oxide layer, the seven individual epitaxial operations being performed under controlled conditions regarding time of exposure, concentration of epitaxial source material, and reaction temperature, so as to permit the nascent YBa.sub.2 Cu.sub.3 O.sub.7 crystal to be stoichiometrically correct and to assume a layered, orthorhombic structure.

A method for making a layered high T.sub.c superconductor by monolayer deposition, comprising the steps of:

• placing a substrate in a chamber, said substrate having a desired crystallographic structure allowing substantial lattice matching to said superconductor, therebeing a plurality of sources in said chamber for providing the constituents of said superconductor,
• heating at least one of said sources to vaporize said source and to cause the constituent in said source to be deposited on said substrate as a monoatomar or monomolecular layer thereon
• heating in a sequence others of said sources to vaporize said sources for deposition onto said substrate of others of said constituents as monoatomar or monomolecular layers thereon,
• said constituents being deposited one at a time,
• repeating said preceding two heating steps to deposit additional monoatomar or monomolecular layers on said substrate until the desired final superconductor is formed.

A method for making artificial, layered high T.sub.c superconductor compounds by monolayer epitaxy, comprising the following steps:

• placing a monocrystalline substrate of a material from the group comprising strontium titanate SrTio.sub.3, zirconium dioxide ZrO.sub.2, zinc telluride Zn.sub.1-x Se.sub.x, barium fluoride, BaF.sub.2, cadmium selenide Cd.sub.1-x, and cadmium telluride Cd.sub.1-x Te.sub.x, wherein x<1, in a chamber having a plurality of independent sources of materials for epitaxial deposition,
• exposing said substrate in a sequence to as many different ones of said sources of constituent materials as the superconductor compounds being made should contain,
• activating said sources in accordance with a pattern of activity, said pattern involving
• determining which particular constituent material is to be deposited at any one time;
• determining the amount and concentration of the particular constituent material to be emitted from said activated source
• determining the period of time the exposure of said substrate to the individual constituent materials should last for one monoatomar/monomolecular layer of the particular constituent material to deposit on the current substrate surface;
• determining the operating temperature at which the exposure is to be performed by monitoring prior to said exposure the operating temperature of the current substrate surface, monitoring prior to said exposure the operating temperature of the source of the particular constituent material and monitoring prior to said exposure the reaction temperature required for the desired high T.sub.c superconductor material to form in accordance with a particular, desired crystal structure;
• repeating the preceding steps as often as corresponds to the number of monomolecular/monoatomar layers the final superconductor compound should contain;
• cooling the resulting crystal to ambient temperature and removing it from said chamber;
• said superconductor contains Cu-O planes;
• and
• wherein the sequence of heating steps deposits monoatomar of monomolecular layers in a sequence other than that naturally occurring.