US5168420A
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Ferroelectrics epitaxially grown on superconducting substrates
Assignee: University of Maryland, College Park
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Filing: 1990-11-20
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Granted: 1992-12-01
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Expires: 2010-11-20
Abstract
Abstract A ferroelectric storage element and its method of growth. A thin ferroelectric film, for example, of bismuth titanate, is epitaxially grown on a perovskite crystalline substrate of thin film that is superconductive at some temperature. For example, the thin film may be YBa2Cu3O7-x, Bi2Sr2CuO6+x, or Bi2Sr2CaCu2O8+x.
Inventors
- 👤 Ramamoorthy Ramesh
- 👤 Jean-Marie Tarascon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:15
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; G; G11; G11C; G11C11/00; G11C11/21; G11C11/22; H01; H01G; H01G7/00; H01G7/06; Y; Y10; Y10T; Y10T29/00; Y10T29/43; Y10T29/435
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
41 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide chosen from the group consisting of cuprate oxide and bismuthal oxide, having a perovskite crystal structure, and being conductive; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 2
Dependent Claim
41 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide chosen from the group consisting of cuprate oxide and bismuthal oxide, having a perovskite crystal structure, and being conductive; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 3
Dependent Claim
32 words
A ferroelectric heterostructure as recited in claim 1, further comprising electrical means connected to said crystalline body and a surface of said ferroelectric layer for applying a voltage across said ferroelectric layer.
Claim 4
Dependent Claim
33 words
A ferroelectric heterostructure as recited in claim 2, further comprising an electrode layer formed over said ferroelectric layer and through which said electric means are connected to said surface of said ferroelectric layer.
Claim 5
Dependent Claim
39 words
A ferroelectric heterostructure as recited in claim 3, wherein said electrical means selectively bias said ferroelectric layer to one of two states that remain after said electrical means ceases biasing said ferroelectric layer, whereby a non-volatile memory is formed.
Claim 6
Dependent Claim
35 words
A ferroelectric non-volatile memory as recited in claim 3, wherein said electrode layer comprises a metal oxide chosen from the group consisting of cuprate oxide and bismuthal oxide, epitaxial with said ferroelectric layer, and conductive.
Claim 7
Dependent Claim
23 words
A ferroelectric heterostructure as recited in claim 3, wherein said metal oxide does not exhibit superconductivity at an operating temperature of said heterostructure.
Claim 8
Dependent Claim
15 words
A ferroelectric heterostructure as recited in claim 1, wherein said ferroelectric layer comprises bismuth titanate.
Claim 9
Dependent Claim
15 words
A ferroelectric heterostructure as recited in claim 1, wherein said ferroelectric layer comprises barium titanate.
Claim 10
Dependent Claim
19 words
A ferroelectric heterostructure as recited in claim 1, wherein said metal oxide is a superconductor at a finite temperature.
Claim 11
Dependent Claim
20 words
A ferroelectric heterostructure as recited in claim 9, wherein said metal oxide comprises Ba 1-x K x BiO 3 .
Claim 12
Dependent Claim
27 words
A ferroelectric heterostructure as recited in claim 1, wherein said metal oxide comprises ReBa 2 Cu 3 O 7-x , wherein Re is a lanthanide rare-earth metal.
Claim 13
Dependent Claim
27 words
A ferroelectric heterostructure as recited in claim 1, further comprising a singly crystalline substrate, wherein said crystalline body is a thin film epitaxial with said crystalline substrate.
Claim 14
Dependent Claim
60 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide which has a perovskite crystal structure and is a superconductor at a finite temperature wherein said metal oxide comprises Bi 2 Sr 2 Ca n-1 Cu n O y , wherein n is an integer greater than zero; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 15
Dependent Claim
60 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide which has a perovskite crystal structure and is a superconductor at a finite temperature wherein said metal oxide comprises Bi 2 Sr 2 Ca n-1 Cu n O y , wherein n is an integer greater than zero; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 16
Independent Claim
62 words
A method of forming a ferroelectric device, comprising the steps of: epitaxially depositing a ferroelectric layer upon a conductive singly crystalline body comprising a metal oxide chosen from the group consisting of a cuprate oxide and a bismuthal oxide and having a perovskite crystal structure; and operatively connecting electrical leads to said body and to an upper surface of said ferroelectric layer.
Claim 17
Independent Claim
62 words
A method of forming a ferroelectric device, comprising the steps of: epitaxially depositing a ferroelectric layer upon a conductive singly crystalline body comprising a metal oxide chosen from the group consisting of a cuprate oxide and a bismuthal oxide and having a perovskite crystal structure; and operatively connecting electrical leads to said body and to an upper surface of said ferroelectric layer.
Claim 18
Dependent Claim
25 words
A method as recited in claim 14, further comprising a step of: epitaxially depositing said conductive body as a thin film upon a crystalline substrate.
Claim 19
Dependent Claim
16 words
A method as recited in claim 15, wherein said two depositing steps comprise pulsed energy evaporation.
Claim 20
Dependent Claim
16 words
A method as recited in claim 16, wherein said pulsed energy evaporation uses a pulsed laser.
Claim 21
Dependent Claim
38 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide comprising YBa 2 Cu 3 O 7-x , having a perovskite crystal structure, and being conductive; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 22
Dependent Claim
38 words
A ferroelectric heterostructure, comprising: a singly crystalline body comprising a metal oxide comprising YBa 2 Cu 3 O 7-x , having a perovskite crystal structure, and being conductive; and a ferroelectric layer epitaxially formed on said crystalline body.
Claim 23
Dependent Claim
16 words
A ferroelectric heterostructure as recited in claim 18, wherein said ferroelectric layer comprises lead zirconate titanate.
Claim 24
Dependent Claim
87 words
A ferroelectric memory, comprising: a substrate a lower electrode comprising a thin film of a conductive first metal oxide deposited on said substrate; a ferroelectric layer deposited on said lower electrode; an upper electrode comprising a thin film of a conductive second metal oxide deposited on said ferroelectric layer; and electrical means connected to said upper and lower electrodes for selectively biasing said ferroelectric layer to one of two states that remain after said electrical means ceases biasing said ferroelectric layer, whereby a non-volatile memory is formed.
Claim 25
Dependent Claim
87 words
A ferroelectric memory, comprising: a substrate a lower electrode comprising a thin film of a conductive first metal oxide deposited on said substrate; a ferroelectric layer deposited on said lower electrode; an upper electrode comprising a thin film of a conductive second metal oxide deposited on said ferroelectric layer; and electrical means connected to said upper and lower electrodes for selectively biasing said ferroelectric layer to one of two states that remain after said electrical means ceases biasing said ferroelectric layer, whereby a non-volatile memory is formed.
Claim 26
Dependent Claim
20 words
A ferroelectric memory as recited in claim 20, wherein said first and second metal oxides comprise a same metal oxide.
Claim 27
Dependent Claim
21 words
A ferroelectric memory as recited in claim 21, wherein said same metal oxide comprises YBa 2 Cu 3 O 7-x .
Claim 28
Dependent Claim
26 words
A ferroelectric memory as recited in claim 21, wherein said first and second metal oxides are normally conductive at an operating temperature of said ferroelectric memory.
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